nitroarginine and 3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate

The purpose of this study was to investigate the effects of endothelial denudation, inhibitors of nitric oxide (NO) and prostanoid synthesis on vasoconstrictor responses in the perfused rabbit ovarian vascular. The experiments were conducted using an in vitro perfusion system, where the ovarian vascular bed (en bloc) was perfused with Krebs' solution delivered at a constant flow rate using a peristaltic pump. Changes in perfusion pressure, which reflected peripheral resistance, were measured. Results showed that noradrenaline (NA) (10(-9) to 10(-6) mol) induced reproducible dose-dependent vasoconstrictor responses. Vasoconstrictor effects of low doses of noradrenaline were not affected by perfusion of the vascular bed with CHAPS (4.7 mg/ml for 30 s) to remove the endothelium. The same treatment however, significantly reduced responses induced by the higher doses of noradrenaline, thus depressing the maximum response. KCl-induced vasoconstriction was not affected by CHAPS. L-N(G)-nitroarginine (L-NOARG) (10(-5) mol/l) enhanced NA-induced vasoconstriction. D-NOARG, the inactive isomer of L-NOARG and aminoguanidine, an inhibitor of inducible nitric oxide synthase reduced rather than enhanced noradrenaline-induced responses. Methylene blue (3 x 10(-5) mol/l) and LY 83583 (10(-5) mol/l) produced a potentiation of NA-induced vasoconstrictor responses. Indomethacin (3 x 10(-6) mol/l) did not significantly enhance NA-induced vasoconstriction. The nonselective endothelin antagonist, SB 209670 (10(-7) and 10(-6) mol/l) did not inhibit the vasoconstriction to NA. In conclusion, results are interpreted to suggest that NA-induced vasoconstriction in the perfused rabbit ovarian vascular bed is accompanied by a release of NO and possibly endothelium-derived contracting factor. There was no evidence for a modulation of vasoconstrictor responses by products of arachidonic acid metabolism or endothelins released from the endothelium.

Topics: Animals; Arginine; Cholic Acids; Cyclooxygenase Inhibitors; Detergents; Endothelins; Enzyme Inhibitors; Female; Indomethacin; Methylene Blue; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Norepinephrine; Ovary; Rabbits; Vasoconstriction; Vasoconstrictor Agents

1. We aimed to determine whether there are any changes in responsiveness of the mesenteric arterial beds to phenylephrine (Phe) and KCl in exercise-trained rats, and whether vascular endothelium and/or vascular smooth muscle play a role in these changes. 2. Adult male rats were subjected to a swimming schedule every day for 28-33 days. Studies were performed in vitro using Krebs perfused mesenteric arterial beds. 3. Maximum perfusion pressure responses to KCl and Phe of the mesenteric arterial beds from exercise-trained rats were significantly lower than those from sedentary controls. However, these differences disappeared after blocking the nitric oxide synthase by NG-nitro-L-arginine (L-NOARG). 4. 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate (CHAPS, 3 mg ml(-1), 2 min infusion) caused a significant increase in maximum perfusion pressure responses to KCl to the same extent in both exercise-trained and sedentary control rats. CHAPS caused about a 4.5 fold leftward shift of the curve with no change in maximum response to Phe for the mesenteric arterial beds from sedentary control rats, but not for those obtained from exercise-trained rats. However, these differences were abolished in the presence of L-NOARG. 5. Indomethacin did not alter the dose-response curves to KCl or Phe in either swimming or control groups. 6. These results suggest that there was a lower vascular responsiveness to KCl and Phe in exercise-trained rats at rest. The decrease in reactivities to KCl or decrease in sensitivity to Phe after having endothelium impairment by CHAPS of the mesenteric arterial beds of exercise-trained rats were due to an increase in both spontaneous release and upregulation of phenylephrine-stimulated release of nitric oxide from both the vascular endothelium and the vascular smooth muscle cells, and may not be a consequence of an increase in vasodilator prostaglandins by the vascular bed.

Topics: Adrenergic alpha-Agonists; Animals; Anti-Inflammatory Agents, Non-Steroidal; Body Weight; Cholic Acids; Detergents; Endothelium, Vascular; Enzyme Inhibitors; Indomethacin; Male; Mesenteric Arteries; Muscle, Smooth, Vascular; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nitroarginine; Phenylephrine; Physical Conditioning, Animal; Potassium Chloride; Rats; Rats, Wistar; Swimming

We examined the possible existence of a novel endothelium-derived relaxing factor in the endothelium of the perfused rat kidney. Acetylcholine-induced vasodilatation was abolished by treatment with NG-nitro-L-arginine (L-NNA) and methylene blue in isotonic high K+ (60 mM) medium, whereas cyclopiazonic acid (CPA)-induced vasodilatation of the perfused kidney was slightly increased by this treatment. When the kidney was perfused with 0.47% CHAPS solution for 1 min, acetylcholine- or cyclopiazonic acid-induced vasodilatation was almost abolished. Acetylcholine- or cyclopiazonic acid-induced vasodilatation was not affected by indomethacin. These results suggest that CPA may release a novel endothelium-derived relaxing factor, which is not prostanoids, nitric oxide nor endothelium-derived hyperpolarizing factor in the endothelium of the renal vascular bed.

Topics: Acetylcholine; Animals; Biological Factors; Cholic Acids; Dimethyl Sulfoxide; Endothelium, Vascular; Indoles; Kidney; Male; Muscle Relaxation; Nitric Oxide; Nitroarginine; Rats; Rats, Wistar; Vasodilation; Vasodilator Agents

1. We aimed to determine whether nitric oxide (NO) and/or the endothelium is involved in cholinergic neurogenic vasodilatation in the rat isolated hindquarters. 2. The abdominal aorta was cannulated for perfusion of the rat hindquarters with Krebs bicarbonate solution containing phenylephrine, to induce basal constrictor tone. In the presence of noradrenergic neurone blockade with guanethidine (200 mg kg-1, i.p.) electrical stimulation of peri-aortic nerves induced frequency-dependent decreases in hindquarters perfusion pressure, indicating vasodilatation. Both the endothelium-dependent vasodilator, acetylcholine (ACh) and the endothelium-independent vasodilator, sodium nitroprusside (SNP) induced dose-dependent decreases in perfusion pressure. In each experiment, responses to either nerve stimulation, ACh or SNP were recorded before and after treatment with saline vehicle, atropine (1 microM), NG-nitro-L-arginine (L-NOARG, 100 microM), L-arginine (1 mM), L-arginine plus L-NOARG, or 3-3 cholamidopropyl dimethylammonio 1-propanesulphonate (CHAPS, 30 mg). Hindquarters dilatation after each treatment was expressed as a percentage of the control response. 3. Following treatment with saline, responses to nerve stimulation and ACh were 99 +/- 9% and 107 +/- 10% of control, respectively demonstrating the reproducibility of these responses. Nerve stimulation-induced dilation was abolished by atropine (0 +/- 0% of control, P < 0.05) or reduced to 14 +/- 10% of control by NO synthase inhibition with L-NOARG (P < 0.05). Dilator responses to ACh were also abolished by atropine (0 +/- 0% of control, P < 0.05) or inhibited by L-NOARG (59 +/- 10% of control, P < 0.05), indicating that the neurogenic dilatation is cholinergic and is mediated by NO. The administration of the NO precursor, L-arginine, prevented the inhibitory effect of L-NOARG on dilator responses to nerve stimulation and ACh (L-arginine plus L-NOARG: 89 +/- 13% and 122 +/- 24% of control, respectively). In addition CHAPS, which removes endothelial cells, inhibited responses to both nerve stimulation (0 +/- 0% of control, P <0.05) and ACh (33 +/- 8% of control, P <0.05). In contrast,no treatment significantly reduced the vasodilator responses to SNP.4. These observations suggest that cholinergic neurogenic vasodilatation in the rat isolated hindquarters requires the synthesis and release of NO from the endothelium.

Topics: Acetylcholine; Animals; Arginine; Atropine; Blood Pressure; Cholic Acids; Electric Stimulation; Endothelium, Vascular; Female; Hindlimb; Male; Nitric Oxide; Nitroarginine; Nitroprusside; Parasympathetic Nervous System; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Vasodilation

Arterioles of hamster cheek pouches are less reactive to luminal application of small hydrophilic agents than to adventitial application. To explore possible longitudinal variations in response sidedness, we compared reactivity of isolated vessels from carotid arteries to first-order arterioles. Concentration-response curves for luminally or adventitially applied phenylephrine (PE) were constructed. Arterioles were 274-fold less responsive when PE was in luminal vs. adventitial responsiveness decreased as vessel diameters increased, from 24-fold in inferior saccular arteries to 18-fold in external maxillary arteries and, finally, to 3-fold in common carotid arteries. Differences in response to luminal or adventitial application of PE could be eliminated in arterioles by perfusion with 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS), which disrupts membrane integrity. Treatment with CHAPS also increased the transmural movement of sodium fluorescein across arteriolar vessel walls. We conclude that a diffusion barrier exists in arterial walls, that there is a longitudinal variation in this barrier as expressed by the differences in movement of small hydrophilic molecules from lumen to smooth muscle cell layers, and that the site of the barrier is likely to be at the endothelial cell membrane.

Topics: Animals; Arginine; Arterioles; Blood Vessels; Capillary Permeability; Carotid Arteries; Cheek; Cholic Acids; Cricetinae; Dose-Response Relationship, Drug; Endothelium, Vascular; Fluorescence; Male; Mesocricetus; Nitroarginine; Phenylephrine; Tunica Intima; Vascular Resistance

The effect of DL-propranolol on NO release in perfused rat hindquarters was studied by using oxyhemoglobin as a capture system to allow the quantitative assay of NO production. In some experiments the stable prostacyclin metabolite 6-keto-PGF1 alpha (6-keto) was simultaneously assayed. We observed that: (1) DL-propranolol induced an increase in NO and 6-keto release. The dextro isomer was inactive; (2) DL-propranolol-induced NO release was only slightly reduced by acetylsalicylic acid in a concentration that inhibits prostacyclin synthesis, and was abolished by the chemical removal of the endothelium with 3-3 cholamidopropyl dimethylammonium 1-propane sulphonate (CHAPS) applied before or during stimulation; (3) NG-nitro-L-arginine blocked DL-propranolol-induced NO production, an effect that was antagonized by L-arginine but not by its dextro isomer.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arginine; Aspirin; Atropine; Carbachol; Cholic Acids; Endothelium, Vascular; Epoprostenol; Male; Nitric Oxide; Nitroarginine; Oxyhemoglobins; Propranolol; Rats; Rats, Inbred Strains

1. The vasoconstrictor activities of endothelin-2, endothelin-3, sarafotoxin S6b, human proendothelin1-38 and mouse vasoactive intestinal contractor (VIC) were studied in the isolated Krebs-Henseleit perfused mesenteric arterial bed of the rat in the presence and absence of the endothelium. The vasoconstrictor properties of endothelin-1 were studied in control preparations and in preparations treated with methylene blue or N omega-nitro-L-arginine methyl ester (NAME). Finally, the direct vasodilator properties of endothelin-2, endothelin-3 and sarafotoxin S6b were studied in preparations preconstricted with methoxamine. 2. In the presence of an intact endothelium, all of the peptides caused dose-dependent increases in perfusion pressure and sarafotoxin S6b was a full agonist relative to the other peptides studied (maximum increase in perfusion pressure, Rmax = 106 +/- 11 mmHg). Endothelin-1, endothelin-2 and VIC were more potent vasoconstrictors (ED50 93.0 +/- 40.0, 90.8 +/- 20.5 and 106 +/- 63 pmol, respectively) than endothelin-3 and sarafotoxin S6b, which were found to be equipotent (ED50 values 411 +/- 195 and 345 +/- 86 pmol, respectively). A full dose-response relationship could not be constructed for proendothelin, but the highest dose used (4 nmol) increased the perfusion pressure by 15.4 +/- 1.6 mmHg. 3. Destruction of the endothelium with the zwitterionic detergent 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate (CHAPS) significantly enhanced the pressor activity of all 5 peptides. The Rmax for sarafotoxin S6b was not significantly altered by removal of the endothelium but its potency was significantly increased (ED50 = 115 +/- 15 pmol). Although their R,,, values were significantly increased, endothelin-2 and VIC were still partial agonists relative to sarafotoxin S6b in CHAPSpretreated preparations; their potencies were unchanged (ED5o values 118 + 53 and 416 + 196pmol, respectively). Removal of the endothelium significantly reduced the potency of endothelin-3 (ED5o, 6.3 + 2.2 nmol) but this peptide then exhibited full agonist activity (R..x = 106 + 14 mmHg). After endothelial cell destruction, the pressor responses to proendothelin were increased; 4 nmol gave a response of 38.8 + 5.5 mmHg. 4. Exposure of preparations to either 100 microM NAME (R,,,X = 42.6 + 2.4mmHg and EDSo = 57.5 + 13.7 pmol) or 10 microM methylene blue (R,,,. = 36.0 + 5.1 mmHg and ED50 = 81.5 + 26.1 pmol) significantly enhanced the maximum pressor responses to

Topics: Animals; Arginine; Blood Pressure; Cholic Acids; Endothelins; Endothelium, Vascular; In Vitro Techniques; Male; Mesenteric Arteries; Methylene Blue; Muscle Relaxation; Muscle, Smooth, Vascular; Nitric Oxide; Nitroarginine; Rats; Rats, Inbred Strains; Vasoconstriction; Viper Venoms