n-(1-methylethyl)-1-1-2-trimethylpropylamine and Hypertension--Pulmonary

Hypoxic pulmonary hypertension (HPH) is a serious and potentially devastating chronic disorder of the pulmonary circulation. Attempts to use drugs in the therapy of hypoxic pulmonary hypertension indicated the importance of prevention or reduction of vasoconstriction as well as of the reversal of remodeling within the cardiovascular system. Iptakalim (2,3-dimethyl-N-(1-methylethyl)-2-butylamine), a novel ATP-sensitive potassium channel opener, has the desired effects on hypoxic pulmonary arteries. Iptakalim decreases the elevated mean pressure in pulmonary arteries, and attenuates remodeling in the right ventricle, pulmonary arteries and airways. Moreover, iptakalim has selective antihypertensive effects: it significantly lowers arterial pressure in hypertensive animals, but has little if any effect in normotensive animals. In HPH iptakalim has selective effects on smaller arteries. Long-term iptakalim therapy decreases expression of sulfonylurea receptor 2 and of mRNA of inwardly rectifying potassium channel in smaller arteries of spontaneously hypertensive rats. Iptakalim inhibits the effects of endothelin-1, reduces the intracellular calcium concentration and inhibits the cell cycle in smooth muscle cells of pulmonary arteries. There is no evidence for the development of tolerance to the long-lasting antihypertensive action of iptakalim. At therapeutic doses iptakalim has no effects on the central nervous, respiratory, digestive, or endocrine systems. It has a broad therapeutic range, so that it can be safely used in the therapy of HPH.

Topics: Animals; Antihypertensive Agents; Arteries; Humans; Hypertension, Pulmonary; Hypoxia; KATP Channels; Neovascularization, Pathologic; Potassium Channels, Inwardly Rectifying; Propylamines

The present study aimed to investigate the protective effects of iptakalim, an adenosine triphosphate (ATP)-sensitive potassium channel opener, on the inflammation of the pulmonary artery and endothelial cell injury in a hypoxia-induced pulmonary arterial hypertension (PAH) rat model. Ninety-six Sprague-Dawley rats were placed into normobaric hypoxia chambers for four weeks and were treated with iptakalim (1.5 mg/kg/day) or saline for 28 days. The right ventricle systolic pressures (RVSP) were measured and small pulmonary arterial morphological alterations were analyzed with hematoxylin and eosin staining. Enzyme-linked immunosorbent assay (ELISA) was performed to analyze the content of interleukin (IL)-1β and IL-10. Immunohistochemical analysis for ED1(+) monocytes was performed to detect the inflammatory cells surrounding the pulmonary arterioles. Western blot analysis was performed to analyze the expression levels of platelet endothelial cell adhesion molecule-1 (PECAM-1) and endothelial nitric oxide synthase (eNOS) in the lung tissue. Alterations in small pulmonary arteriole morphology and the ultrastructure of pulmonary arterial endothelial cells were observed via light and transmission electron microscopy, respectively. Iptakalim significantly attenuated the increase in mean pulmonary artery pressure, RVSP, right ventricle to left ventricle plus septum ratio and small pulmonary artery wall remodeling in hypoxia-induced PAH rats. Iptakalim also prevented an increase in IL-1β and a decrease in IL-10 in the peripheral blood and lung tissue, and alleviated inflammatory cell infiltration in hypoxia-induced PAH rats. Furthermore, iptakalim enhanced PECAM-1 and eNOS expression and prevented the endothelial cell injury induced by hypoxic stimuli. Iptakalim suppressed the pulmonary arteriole and systemic inflammatory responses and protected against the endothelial damage associated with the upregulation of PECAM-1 and eNOS, suggesting that iptakalim may represent a potential therapeutic agent for PAH.

Topics: Animals; Blood Pressure; Cell Hypoxia; Disease Models, Animal; Endothelium, Vascular; Enzyme-Linked Immunosorbent Assay; Hemodynamics; Hypertension, Pulmonary; Immunohistochemistry; Interleukin-10; Interleukin-1beta; KATP Channels; Lung; Male; Nitric Oxide Synthase Type III; Platelet Endothelial Cell Adhesion Molecule-1; Propylamines; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Trachea

To study the selective dilatation effects of iptakalim (Ipt), a novel ATP-sensitive potassium channel opener, on pulmonary arterioles in hypoxic pulmonary hypertensive rat.. SD male rats were divided into 3 groups, control group, the rest were fed in hypoxic and normobaric environment (O2 10% +/- 0.5%, 8 h/d and 6 d/week) and divided into hypoxia group and hypoxia plus acetazolamide (Acz) group (hypoxic rats were treated with ig acetazolamide (Acz) 80 mg x kg(-1) d(-1)) . After 12 weeks, pulmonary arteriole rings about (197 +/- 4) microm were isolated and the tension of hypoxic pulmonary arterioles pre-contracted by 6 nmol/L endothelin-1 (FT-1) was observed with wire myograph system model (DMT 610 m). The relaxing response of hypoxic pulmonary arterioles induced by different concentration of Ipt were detected and endothelial activity was also tested by acetylcholine.. 10(-5) mol/L acetylcholine (ACh)-mediated vasodilatation was greatly reduced in the hypoxic group than those in control group (P < 0.01) and there was no significant difference between Acz treatment group and control group (P > 0.05). Ipt at the concentration ranging from 10(-11) mol/L to 10(-4) mol/L, caused dose dependent vasodilation on both hypoxic pulmonary arterioles and Acz treatment group (P > 0.05), but not on normal group.. The endothelial function of pulmonary arterioles was damaged under hypoxic pulmonary hypertensive state, and Ipt showed selective dilatation effects on hypoxic pulmonary arterioles. Acz could improve the dysfunction of endothelial cells induced by hypoxic pulmonary hypertensive state, which didn't affect the selective dilatation effects of Ipt on hypoxic pulmonary arterioles.

Topics: Acetazolamide; Animals; Arterioles; Hypertension, Pulmonary; Hypoxia; Male; Propylamines; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Vasodilator Agents

We sought to investigate the experimental therapeutic effects and mechanisms of iptakalim, a new adenosine triphosphate (ATP)-sensitive potassium channel (K(ATP)) opener, on monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and right heart ventricle remodeling in rats.. Rats were injected with a single dose (50 mg/kg, ip) of MCT and given iptakalim (1, 3, and 9 mg/kg·per d, orally [po]) or saline for 28 days. The hemodynamic and morphometric parameters were assessed. Tissue and plasma samples were collected for histological and molecular analysis.. Treatment with iptakalim at daily oral doses of 1, 3, and 9 mg/kg from the day of MCT injection attenuated the high right ventricle systolic pressure (RVSP) and the increased weight ratio of right ventricle (RV) to left ventricle (LV) plus septum (S) (RV/(LV+S)), decreased heart rate (HR) and decreased mean arterial pressure (MAP), inhibited the RV myocardial tissue cell apoptosis, and the RV myocardial cell B-type natriuretic peptide (BNP) protein expression. Iptakalim also decreased the serum levels of nitric oxide (NO), endothelin 1 (ET-1), BNP, and the levels of NO, ET-1, and tumor necrosis factor-alpha (TNF-α) in the lung tissue.. These results indicate that iptakalim prevents MCT-induced PAH and RV remodeling and its mechanisms are related to inhibiting the pathological increases in NO, ET-1, BNP, and TNF-α, and Iptakalim may be a promising candidate for the treatment of PAH.

Topics: Animals; Endothelin-1; Familial Primary Pulmonary Hypertension; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; KATP Channels; Lung; Male; Monocrotaline; Natriuretic Peptide, Brain; Nitric Oxide; Propylamines; Rats; Rats, Wistar

Hypoxic pulmonary hypertension (HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries. The aim of specific therapies for hypoxic pulmonary hypertension is to reduce pulmonary vascular resistance, reverse pulmonary vascular remodeling, and thereby improving right ventricular function. Iptakalim, a lipophilic para-amino compound with a low molecular weight, has been demonstrated to be a new selective ATP-sensitive potassium (K(ATP)) channel opener via pharmacological, electrophysiological, biochemical studies, and receptor binding tests. In hypoxia-induced animal models, iptakalim decreases the elevated mean pressure in pulmonary arteries, and attenuates remodeling in the right ventricle, pulmonary arteries and airways. Furthermore, iptakalim has selective antihypertensive effects, selective vasorelaxation effects on smaller arteries, and protective effects on endothelial cells, but no effects on the central nervous, respiratory, digestive or endocrine systems at therapeutic dose. Our previous studies demonstrated that iptakalim inhibited the effects of endothelin-1, reduced the intracellular calcium concentration and inhibited the proliferation of pulmonary artery smooth muscle cells. Since iptakalim has been shown safe and effective in both experimental animal models and phase I clinical trials, it can be a potential candidate of HPH in the future.

Topics: Animals; Antihypertensive Agents; Calcium; Disease Models, Animal; Endothelin-1; Hypertension, Pulmonary; Hypoxia; KATP Channels; Myocytes, Smooth Muscle; Propylamines; Pulmonary Artery

To explore the effects of iptkalim on myocardial enzymes and free radicals metabolism with hypoxic pulmonary hypertension (HPH), in order to provide evidence for the mechanism of iptkalim on clinical treat.. 110 young men stayed at high altitude above 5 000 m were divided into iptkalim group (n = 74) and placebo group (n = 36), aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (gamma-GT), creatine kinase (CK), lactate dehydrogenase (LDH), superoxide dismutase (SOD), malonaldehyde (MDA), nitric oxide(NO) and nitric oxide synthase(NOS) were detected before and after took medicines for 6 mouths.. After took medication for 6 mouths, ALT, AST, gamma-GT, CK and LDH were reduced, SOD, NO, and NOS were increased, MDA were reduced, there were very significant difference (P < 0.05).. Oxygen free radicals have taken part in the process of HPH, iptkalim have the effect of anti-peroxidation of lipid and protect myocardial cells stress injured by hypoxia which related with mitochondrial membrane and cell membrane's K(ATP) channel activation.

Topics: Adolescent; Adult; Altitude; Creatine Kinase; Free Radicals; Humans; Hypertension, Pulmonary; Hypoxia; L-Lactate Dehydrogenase; Male; Myocardium; Potassium Channels; Propylamines; Young Adult

To investigate whether pulmonary vascular remodeling in hypoxic pulmonary hypertensive rats could be prevented by treatment with a selective K(ATP)CO, iptkalim (Ipt).. Rats were fed in hypoxic and normobaric environment (10% +/- 0.5% O2, 8 h/day and 6 day/week) and divided into control group, hypoxia group (hypoxic rat treated with ig NS 5.0 ml x kg(-1) x d(-1)), treated group I (hypoxic rat treated with ig Ipt 0.75 mg x kg(-1) x d(-1)), treated group II (hypoxic rat treated with ig Ipt 1.5 mg x kg(-1) x d(-1)). After 4 wk, the mean pulmonary arterial pressure (mPAP), right ventricle/left ventricle and septum [RV/(LV + S)] were measured, and the small pulmonary arterial morphologic changes were observed with morphometric analysis under microscopes in four groups.. The level of mPAP and RV/(LV+ S) was significantly higher in the hypoxic group than those in control group (P < 0.01). Morphometric analysis revealed that the ratio of vascular medial wall thickness to external diameter (MT%) and the ratio of vascular medial cross-sectional area to total arterial cross-sectional area (MA%) were also significantly increased in the hypoxic group than those in control group (P < 0.01) and the ratio of vessel lumen cross-sectional area to total arterial cross-sectional area (VA%) was significantly lower in the hypoxic group than those in control group (P < 0.01). Ipt 0.75 mg x kg(-1) x d(-1) or 1.5 mg x kg(-1) x d(-1) decreased the level of mPAP(mmHg), RV/(LV+ S), and inhibited the small pulmonary arterial remodeling significantly. Ipt 1.5 mg x kg(-1) x d(-1) reversed all pathological indices.. K(ATP)CO iptkalim can be a very promising candidate for the treatment of hypoxic pulmonary hypertension.

Topics: Animals; Hypertension, Pulmonary; Hypoxia; KATP Channels; Male; Propylamines; Rats; Rats, Sprague-Dawley