15-hydroxy-11-alpha-9-alpha-(epoxymethano)prosta-5-13-dienoic-acid and Coronary-Vasospasm

Previous reports showed that 17beta-estradiol implants attenuate in vivo coronary hyperreactivity (CH), characterized by long-duration vasoconstrictions (in coronary angiographic experiments), in menopausal rhesus monkeys. Prolonged Ca2+ contraction signals that correspond with CH in coronary vascular muscle cells (VMC) to the same dual-constrictor stimulus, serotonin + the thromboxane analog U-46619, in estrogen-deprived VMC were suppressed by >72 h in 17beta-estradiol. The purpose of this study was to test whether an endogenous estrogen metabolite with estrogen receptor-beta (ER-beta) binding activity, estriol (E3), suppresses in vivo and in vitro CH. E3 treatment in vivo for 4 wk significantly attenuated the angiographically evaluated vasoconstrictor response to intracoronary serotonin + U-46619 challenge. In vitro treatment of rhesus coronary VMC for >72 h with nanomolar E3 attenuated late Ca2+ signals. This reduction of late Ca2+ signals also appeared after >72 h of treatment with subnanomolar 5alpha-androstane-3beta,17beta-diol (3beta-Adiol), an endogenous dihydrotestosterone metabolite with ER-beta binding activity. R,R-tetrahydrochrysene, a selective ER-beta antagonist, significantly blocked the E3- and 3beta-Adiol-mediated attenuation of late Ca2+ signal increases. ER-beta and thromboxane-prostanoid receptor (TPR) were coexpressed in coronary arteries and aorta. In vivo E3 treatment attenuated aortic TPR expression. Furthermore, in vitro treatment with E3 or 3beta-Adiol downregulated TPR expression in VMC, which was blocked for both agonists by pretreatment with R,R-tetrahydrochrysene. E3- and 3beta-Adiol-mediated reduction in persistent Ca2+ signals is associated with ER-beta-mediated attenuation of TPR expression and may partly explain estrogen benefits in coronary vascular muscle.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Administration, Cutaneous; Androstane-3,17-diol; Animals; Calcium Signaling; Chrysenes; Coronary Vasospasm; Estriol; Estrogen Receptor beta; Female; Gene Expression; Genistein; Macaca mulatta; Muscle, Smooth, Vascular; Nitriles; Propionates; Receptors, Thromboxane; Serotonin; Vasoconstriction

In the present investigation, we test the hypothesis that progesterone can rapidly relax, via a nongenomic mechanism, persistent flow occluding, agonist-activated coronary artery (CA) vasospasm, and hyperreactive vascular muscle cell (VMC) Ca(2+) responses in ovariectomized rhesus monkeys. CA vasospasm, induced by injection of 100 microM serotonin and 1 microM U-46619 (5-HT+U; 1 ml/30 s), resulted in a decrease in CA diameter (phi) from 1.8 +/- 0.2 to 0.3 +/- 0.1 mm at the site of focal constriction. Injection of 100 ng progesterone into the CA significantly relieved the severe vasoconstriction (1.3 +/- 0.2 mm) and reestablished distal flow in 3 min; the preconstriction phi was completely restored in 8.2 +/- 2.6 min (n = 6). Similarly, cell impermeant albumin-conjugated progesterone, but not albumin-conjugated 17 beta-estradiol, decreased 5-HT+U stimulated VMC Ca(2+) responses (250 +/- 34% of basal 30 min after stimulation) back to the prestimulation level (113 +/- 17% of basal) in 25 min (half time = 7 min). The presence of a rapid vasodilator action of progesterone in the primate CA and isolated VMC suggests its benefits in hormone replacement therapy may also include nongenomic vascular relaxant actions.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Calcium; Coronary Vasospasm; Coronary Vessels; Drug Combinations; Estradiol; Female; Injections, Intra-Arterial; Macaca mulatta; Muscle, Smooth, Vascular; Ovariectomy; Progesterone; Serotonin; Serum Albumin, Bovine; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

We hypothesized that progesterone regulates thromboxane A(2) receptor (TxA(2)R) density in primate vascular muscle and that TxA(2)R density correlates with coronary reactivity in vivo and in vitro. Reactivity to serotonin + U-46619 was determined by angiography in surgically postmenopausal [ovariectomized (Ovx)] rhesus monkeys without progesterone replacement and after 2-wk progesterone treatment (1-2 ng/ml). In untreated Ovx animals, 100 micromol/l serotonin + 1 micromol/l U-46619 (syringe concentrations) provoked vasospasm-like constrictions in six of six monkeys; zero of six progesterone-treated monkeys developed vasospasms. Sustained Ca(2+) responses in vascular muscle cells isolated from Ovx coronaries (208 +/- 63% of basal 20 min after stimulation) treated with serotonin + U-46619 contrasted with transient Ca(2+) responses (143 +/- 18% of basal and decreasing 5 min after stimulation) in progesterone-treated monkeys. The maximum density of [1S-(1I,2J(5Z),3I(1E,3R*),4I)]-7-[3-(3-hydroxy-4-(4'-[(125)I]iodophenoxy)- 1-butenyl)-7-oxabicyclo[2.2.1]heptan-2-yl]-5-heptenoic acid ([(125)I]-BOP) binding was greater (P < 0.01) in carotid arteries and aortic membranes from Ovx (109 +/- 11 fmol/mg) compared with progesterone-treated (43 +/- 15 fmol/mg) monkeys. TxA(2)R immunolabeling revealed greater coronary TxA(2)R labeling in Ovx compared with progesterone-treated monkeys. The results suggest that progesterone can decrease arterial TxA(2)R in Ovx monkeys.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Coronary Vasospasm; Coronary Vessels; Female; Immunohistochemistry; In Vitro Techniques; Intracellular Membranes; Macaca mulatta; Muscle, Smooth, Vascular; Ovariectomy; Postmenopause; Progesterone; Protein Kinase C; Radioligand Assay; Receptors, Thromboxane; Serotonin; Signal Transduction; Vasoconstriction; Vasoconstrictor Agents; Vasodilation

Susceptibility to drug-induced coronary vasospasm in rhesus monkeys increases after removal of the ovaries and can be normalized by adding back physiological levels of estradiol-17ss (E2) and/or natural progesterone (P) in vivo as reported recently by our group. Furthermore, the reactivity status (Ca2+ and protein kinase C responses) of freshly isolated and primary culture coronary artery vascular muscle cells (VMC) mimic the intact coronary artery responses to 5-HT + U46619. Since coronary reactivity is maintained in the isolated VMC, we hypothesized that the reactivity state inherent in the VMC was modulated directly by ovarian steroids in vitro as in the whole animal. To test this hypothesis, we treated hyperreactive VMC from ovariectomized (ovx) monkeys in vitro with E2 or P and measured VMC reactivity to combined stimulation with 5-HT and U46619, as determined by the amplitude and especially the duration of intracellular Ca2+ signals, as well as protein kinase C (PKC) activation/translocation. VMC were treated for 12 96 h with 3 100 pg/ml E2 (10 365 pM) and/or 0.3 3 ng/ml P (0.95 9.5 nM). Hyperreactive responses to the combination of 5-HT and U46619 in untreated VMC were significantly and dose-dependently reduced by treatment in vitro with physiological levels of either E2 or P for at least 24 h. Both the early transient and late sustained increases in intracellular Ca2+ and PKC translocation were blunted, and the effects of 0.2 nM E2 and 3.2 nM P were specifically antagonized by the receptor blockers ICI 182,780 (200 nM) and RU486 (15 nM), respectively. Antibodies to the estrogen receptor and progesterone receptor labeled nuclei in VMC, which were also positively labeled by a smooth muscle myosin heavy chain monoclonal antibody. These data indicate that natural ovarian steroids directly reduce hyperreactive 5-HT and thromboxane A2-stimulated Ca2+ and PKC responses of coronary artery VMC from surgically menopausal rhesus macaques. We hypothesize that vascular hyperreactivity, which may be a critical factor involved in the increased incidence of coronary artery vasospasm and ischemic heart disease in postmenopausal women, can be normalized by E2 and/or P through direct actions on coronary artery vascular muscle cells.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Calcium Signaling; Coronary Vasospasm; Coronary Vessels; Disease Models, Animal; Disease Susceptibility; Enzyme Activation; Estradiol; Estrogen Antagonists; Female; Fulvestrant; Hormone Antagonists; Hormone Replacement Therapy; Humans; Macaca mulatta; Microscopy, Confocal; Microscopy, Fluorescence; Mifepristone; Muscle Proteins; Muscle, Smooth, Vascular; Ovariectomy; Postmenopause; Progesterone; Protein Kinase C; Receptors, Estrogen; Receptors, Progesterone; Serotonin; Thromboxane A2; Vasoconstriction

We studied the hypothesis that in the absence of vascular pathology, coronary artery vasospasm occurs as a result of local regions of vascular muscle hyperreactivity. We aimed to explore the basis for a functional etiology of those vasospasms not explained on a structural basis.. Ovariectomized rhesus monkeys (Macaca mulatta) without injury or significant vascular disease were stimulated with platelet release products, and angiograms were compared with those from vasospasms induced in human patients.. We used intracoronary (IC) injections of serotonin, thromboxane A2 (U46619), endothelin 1 or angiotensin II in concentrations 3 to 10 times that which reduced coronary artery diameter by 50%.. Although no agent alone caused vasospasm, the combination of pathophysiologic concentrations of serotonin and the stable thromboxane A2 mimetic, U46619, injected through an IC catheter, synergistically caused coronary vasospasm on the second or third challenge in five of seven monkeys. These drug-induced vasospasms were similar to vasospasms induced by mechanical injury followed by serotonin, and to those stimulated in human IC diagnostic tests, as judged by onset, appearance, kinetics and vasodilator reversal.. These studies in ovariectomized monkeys revealed that coronary vasospasm can be stimulated without preexisting vascular pathology, endothelial denudation or injury. Reproducible vasospasm of primate coronary arteries in response to these two endogenous pathophysiologic vasoconstrictors, which are thought to be precipitating stimuli in the etiology of vasospasm, suggests that structure-independent epicardial vasospasm can be an important element in serious cardiac ischemic events, particularly the focal, persistent vasospasms that occur without plaques or injury.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Coronary Angiography; Coronary Vasospasm; Coronary Vessels; Female; Macaca mulatta; Male; Muscle, Smooth, Vascular; Prostaglandin Endoperoxides, Synthetic; Thromboxane A2; Vasoconstrictor Agents

Cellular mechanisms of protection against drug-stimulated coronary vasospasm were studied by multiweek estrogen plus progesterone (P) vs. medroxy-progesterone acetate (MPA) treatments by measuring intracellular Ca2+ and protein kinase C (PKC) signals. Ovariectomized monkeys (OVX) were treated by slow-release implants with either P or MPA for 4 wk added to estradiol-17 beta (E2) begun 2 wk earlier. A third group received E2 for 2 wk and withdrawal of E2 (W; no steroid treatment) during the last 4 wk. OVX coronary artery vascular muscle cells (VMC) in primary culture conditions were labeled by the fluorescent indicators, fluo 3 and hypericin, respectively, to study intracellular Ca2+ and PKC mechanisms of coronary artery hyperre-activity, using digital analysis of single VMC by photon-counting camera. Stimulation by 10 microM serotonin and 100 nM U-46619 (thromboxane A2 mimetic) caused Ca2+ increases (2-5 min) and no PKC activation in VMC from five P-treated monkeys but prolonged (> or = 30 min) increases in both Ca2+ and PKC signals in VMC from six MPA-treated monkeys or seven W-treated monkeys; these P vs. MPA (or W) differences were maintained > or = 14 days. We hypothesize that hyperreactivity in VMC from MPA- or W-treated monkeys results from accelerated prolonged Ca2+ release, with concomitant PKC activation, and that MPA (but not P) negates the coronary vasospasm protective effect of E2.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Calcium; Cells, Cultured; Coronary Vasospasm; Coronary Vessels; Drug Combinations; Estrogens; Female; Macaca mulatta; Medroxyprogesterone Acetate; Muscle, Smooth, Vascular; Ovariectomy; Progesterone; Progesterone Congeners; Prostaglandin Endoperoxides, Synthetic; Protein Kinase C; Serotonin; Thromboxane A2; Tissue Distribution; Vasoconstrictor Agents

Reperfusion of the ischemic myocardium is a cornerstone of current therapy for acute coronary syndromes. Experiments show that reperfusion is associated with injury to the coronary artery. Such injury may manifest as augmented vasospasm or impaired vasodilation, and in this study we assessed whether such coronary responses to serotonin do occur.. Left anterior descending arteries (LAD) were occluded in 12 open-chested dogs for 1 h, then reperfused for 1 h. Vasoreactivity to serotonin was measured in isolated rings from the LAD and circumflex arteries (Cx), both at basal resting tension and after preconstriction with U-46619. Endothelium was removed in half of the rings.. In the basal state, LAD rings displayed increased initial constriction and decreased dilation in response to serotonin (maximum dilation: LAD, -4.5 +/- 1.7% versus Cx, -7.6 +/- 1.4%, P < 0.05). With endothelium removed, peak constrictions of the LAD and Cx were significantly augmented, and LAD dilations remained slightly impaired compared with the Cx. After U-46619, dilation in response to serotonin was impaired in the LAD compared with Cx rings (maximum dilation: LAD, -18.3 +/- 11.4% versus Cx, -44.0 +/- 8.4 LAD, P < 0.05). Endothelium removal diminished, but did not abolish, this relationship. De-endothelialized Cx, but not LAD, rings displayed slightly impaired dilations in response to serotonin compared with their respective controls.. After ischemia-reperfusion, coronary arteries respond to serotonin with enhanced constriction and impaired dilation. Changes in both the endothelium and the smooth muscle may determine these responses to serotonin.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Coronary Vasospasm; Coronary Vessels; Dogs; Endothelium, Vascular; Male; Muscle, Smooth, Vascular; Myocardial Ischemia; Myocardial Reperfusion; Myocardial Reperfusion Injury; Potassium Chloride; Prostaglandin Endoperoxides, Synthetic; Serotonin; Thromboxane A2; Vasoconstrictor Agents; Vasodilation

To determine the effect of 1.5 MAC of two volatile anesthetics (halothane and isoflurane) on platelet-induced contraction of canine coronary artery, isolated, denuded coronary rings were suspended between two stirrups, placed into organ chambers filled with an oxygenated Krebs-Ringer solution, and connected to an isometric force transducer. Human platelets were obtained from healthy donors and introduced into the organ chambers in increasing amounts to reach 20,50 and, 70 x 10(9) platelets/L. The tension generated in both the control and anesthetic-treated rings was recorded; only halothane reduced the tension induced by platelet activation in the organ chambers. In some experiments, aliquots of Krebs-Ringer solution were taken to determine the amount of 5-HT and TB2 released by 70 x 10(9) human platelets in the presence and absence of the anesthetics. Only halothane reduced TA2 production by the activated platelets. Finally, the contractile response of isolated denuded canine coronary artery rings to U46619, a thromboxane analog, was measured in the presence and absence of the anesthetics. Neither halothane nor isoflurane attenuated the response. In another series of experiments, in vitro platelet aggregation was induced by epinephrine, collagen, ADP, or arachidonic acid in the presence or absence of 1.5 MAC isoflurane or halothane. Both anesthetics significantly reduced the aggregation.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Blood Platelets; Coronary Vasospasm; Coronary Vessels; Dogs; Dose-Response Relationship, Drug; Female; Halothane; Humans; Isoflurane; Male; Muscle, Smooth, Vascular; Platelet Activation; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic; Serotonin; Thromboxane A2; Thromboxane B2; Vasoconstriction; Vasoconstrictor Agents; Vasomotor System

Illicit cocaine use has been associated with a high incidence of cardiovascular complications including coronary spasm, arrhythmias, myocardial infarction and sudden death. Adverse effects of cocaine have been attributed routinely to the consequences of increased concentrations of the adrenergic transmitter at its sites of action including the coronary vasculature. The present study examined non-neurogenic postsynaptic sites of cocaine action in cattle coronary arteries that could account for its clinical profile. It was found that cocaine (3.3 x 10(-5) M) greatly increased responses to potassium chloride (by 98.4 +/- 13.8%) that are totally dependent on extracellular calcium. However, contractions to a thromboxane A2 analog, which are much less dependent on extracellular calcium influx, were not increased significantly by cocaine. Cocaine (3.3 x 10(-5) M) more than doubled the magnitude of non-neurogenic responses to field stimulation, but these responses were not enhanced in the presence of a calcium channel antagonist. Spontaneously generated tone was magnified significantly by cocaine (3.3 x 10(-5) M) (by 127.5 +/- 45.2%), and this enhancement also was selectively antagonized by nifedipine. Subthreshold concentrations of the calcium channel opener, Bay K 8644, also were increased greatly by cocaine, and this magnification was antagonized by nifedipine. Cocaine did not magnify responses to norepinephrine that are inhibitory in cattle coronary arteries, and desmethylimipramine, a potent inhibitor of catecholamine uptake, had no sensitizing effects on responses to potassium chloride, norepinephrine or field stimulation. It is concluded that cocaine has a potent action on the calcium L channels, magnifying the effects of stimuli that make use of these channels in contractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; Animals; Calcium Channel Blockers; Calcium Channels; Cattle; Cocaine; Coronary Vasospasm; Coronary Vessels; Desipramine; Electric Stimulation; In Vitro Techniques; Norepinephrine; Potassium; Prostaglandin Endoperoxides, Synthetic; Vasoconstriction

The spasmolytic effects of nicorandil, cromakalim, and nitroglycerin on coronary arteries were investigated by angiographic technique in anesthetized dogs. With intracoronary arterial (i.a.) U 46619, a thromboxane A2 mimetic, the diameter of coronary arteries decreased in a sustained manner by 36.1 +/- 1.6% from control levels (coronary spasm). With a successive i.a. injection of nicorandil (300 micrograms), cromakalim (30 micrograms), or nitroglycerin (3 micrograms), the diameter recovered control levels (102.9 +/- 3.9, 96.8 +/- 5.6, and 100.1 +/- 4.3%, respectively). In dogs treated intravenously (i.v.) with glibenclamide, a pharmacologic antagonist of K-channel openers, the spasmolytic effect of cromakalim was significantly reduced, whereas the activity of nicorandil or nitroglycerin remained unaffected. We also investigated a possible modification by glibenclamide of the increase in coronary blood flow (CBF) induced by i.a. nicorandil and cromakalim in anesthetized dogs. The dose-dependent blood flow responses to cromakalim and nicorandil were significantly attenuated by glibenclamide, whereas the response to nitroglycerin remained unaffected. These results suggest that the spasmolytic effect of nicorandil on canine conductive coronary vessels is not mediated by K-channel opening but by a nitroglycerin-like action and that the dilatation of resistive coronary vessels induced by nicorandil may be largely due to its action as a K-channel opener.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Angiocardiography; Animals; Benzopyrans; Coronary Circulation; Coronary Vasospasm; Coronary Vessels; Cromakalim; Dogs; Female; Glyburide; Male; Niacinamide; Nicorandil; Nitroglycerin; Parasympatholytics; Potassium Channels; Prostaglandin Endoperoxides, Synthetic; Pyrroles; Vasodilator Agents

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arachidonic Acid; Arachidonic Acids; Aspirin; Blood Platelets; Cattle; Coronary Vasospasm; Coronary Vessels; Eicosanoic Acids; Humans; In Vitro Techniques; Methysergide; Muscle, Smooth, Vascular; Prostaglandin Endoperoxides, Synthetic; Salicylates; Salicylic Acid; Vasoconstriction

We studied the effects of the thromboxane analog, U46619, infused into the left anterior descending (LAD) artery of intact dogs before and after producing endothelial denudation of the mid portion of the LAD. Proximal artery cross-sectional area (CSA) decreased by 47% with 0.1 microgram/min infusion of U46619 with intact and denuded endothelium, while resting CSA reduced spontaneously following denudation. Coronary resistance vessels demonstrated a marked constrictor response to U46619 with a rise in resistance and a fall in flow and myocardial O2 consumption. U46619 produces significant narrowing of proximal epicardial coronary arteries as well as resistance coronary vessels. This effect could cause ischemia in patients with moderate coronary atherosclerosis.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Coronary Disease; Coronary Vasospasm; Coronary Vessels; Disease Models, Animal; Dogs; Endothelium; Male; Oxygen Consumption; Prostaglandin Endoperoxides, Synthetic; Regional Blood Flow; Vascular Resistance; Vasoconstriction