title: Effects and underlying mechanisms of human opiorphin on cardiovascular activity in anesthetized rats.
abstract: The present study was performed to investigate the peripheral cardiovascular effects of opiorphin in anesthetized rats. Intravenous (i.v.) injection of opiorphin (50-500nmol/kg) caused marked dose-dependent increase in blood pressure and heart rate. The pressor and tachycardic responses induced by opiorphin (300nmol/kg, i.v.) were significantly decreased by pretreatment with angiotensin-converting enzyme inhibitor captopril or angiotensin II type 1 (AT1) receptor antagonist valsartan, which suggested that endogenous angiotensin may be involved in the response to opiorphin. Pretreatment with α-adrenoreceptor antagonist phentolamine and β-adrenoceptor antagonist propranolol respectively attenuated the pressor response induced by opiorphin. Propranolol, but not phentolamine, inhibited the tachycardic response. Moreover, reserpine blocked both responses to opiorphin. These findings indicated that the effects of opiorphin to increase blood pressure and heart rate might be due to the stimulation of sympathetic ganglia. Additionally, studies with bilaterally adrenalectomized rats showed that adrenal medulla may be involved in the cardiovascular regulation of opiorphin. In addition, pretreatment with nonselective opioid receptor antagonist naloxone did not modify the cardiovascular responses to opiorphin, suggesting that the effects of opiorphin were not related to the opioid system. Furthermore, radioimmunoassay (RIA) showed that opiorphin significantly increased endogenous levels of angiotensin II and angiotensin III. In summary, all the results indicate that the cardiovascular effects induced by opiorphin are mediated through the renin-angiotensin system (RAS), the sympathetic ganglia and adrenal medulla, but not the opioid system.
authors.affiliation: Experimental Teaching Center of Biology, and Institute of Cell Biology, School of Life Sciences, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Xiao-zhu
authors.initials: XZ
authors.lastname: Tian
authors.affiliation: Experimental Teaching Center of Biology, and Institute of Cell Biology, School of Life Sciences, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Experimental Teaching Center of Biology, and Institute of Cell Biology, School of Life Sciences, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Lu
authors.initials: L
authors.lastname: Bai
authors.affiliation: Experimental Teaching Center of Biology, and Institute of Cell Biology, School of Life Sciences, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Pan
authors.initials: P
authors.lastname: Luo
authors.affiliation: Experimental Teaching Center of Biology, and Institute of Cell Biology, School of Life Sciences, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Xue-jing
authors.initials: XJ
authors.lastname: Du
authors.affiliation: Experimental Teaching Center of Biology, and Institute of Cell Biology, School of Life Sciences, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Tropical Crops Genetic Resources Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou 571737, Hainan, PR China. Electronic address: tianxm333333@gmail.com.
authors.forename: Xin-min
authors.initials: XM
authors.lastname: Tian
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002216:Captopril / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D012084:Renin-Angiotensin System / Q000187:drug effects; D012110:Reserpine / Q000494:pharmacology; D012471:Salivary Proteins and Peptides / Q000494:pharmacology*; D013777:Tetrazoles / Q000494:pharmacology; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D000068756:Valsartan
chemical_list: D018759:Adrenergic Uptake Inhibitors; D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D009292:Narcotic Antagonists; D009842:Oligopeptides; D012471:Salivary Proteins and Peptides; D013777:Tetrazoles; C517879:glutaminyl-arginyl-phenylalanyl-seryl-arginine; D009270:Naloxone; D000068756:Valsartan; D012110:Reserpine; D002216:Captopril; D011433:Propranolol; D014633:Valine; D010646:Phentolamine
keywords: Adrenal medulla; Cardiovascular; Human opiorphin; Hypertension; Sympathetic ganglia; Tachycardia