title: Chronic activation of neurokinin-1 receptor induces pulmonary hypertension in rats.
abstract: In this study we explored the hypothesis that chronic activation of neurokinin-1 (NK-1) receptor induces pulmonary hypertension in Wistar rats. First, the activation of NK-1 receptor on the pulmonary circulation was investigated by use of a chronic injection of NK-1 agonist [Ser9,Met(O2)11]-substance P (1 x 10(-9) mol/kg) for 2 wk at sea level (rats breathed room air) and during hypoxia (rats were placed in a hypobaric 380-Torr chamber). Second, we studied the effect of NK-1 antagonist (CP-96345) on developing and developed (after 4 wk of chronic hypoxia) pulmonary hypertension. Pulmonary arterial pressure, the weight ratio of right ventricle to left ventricle + septum, hematocrit, and substance P (SP) were measured. We found that NK-1 agonist significantly increased pulmonary arterial pressure in the sea-level but not in the hypoxic group. However, NK-1 agonist induced neither right heart hypertrophy nor polycythemia. CP-96345 significantly decreased pulmonary arterial pressure in the hypoxic group but had no effect in the sea-level group. Furthermore, CP-96345 significantly attenuated the acute SP-induced increase in pulmonary arterial pressure in the sea-level and hypoxic groups, with a larger increase in the hypoxic group. These results suggest that chronic activation of NK-1 receptor induces pulmonary hypertension and that there is an increase in the sensitivity of pulmonary vessels in response to SP in chronically hypoxic rats.
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001274:Atmospheric Pressure; D001713:Biphenyl Compounds / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D005260:Female; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000378:metabolism*; D017380:Hypertrophy, Right Ventricular / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D064729:Neurokinin-1 Receptor Antagonists; D011669:Pulmonary Wedge Pressure; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*; D018042:Receptors, Neurokinin-3 / Q000037:antagonists & inhibitors; D013373:Substance P / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology