Differential effects of nitroblue tetrazolium on the hemodynamic responses elicited by activation of alpha1-adrenoceptors and 5-HT2 receptors in conscious rats.
This study determined the effects of the lipophobic electron acceptor, nitroblue tetrazolium (5 micromol/kg, i.v.) on the vasoconstrictor responses elicited by the 5-hydroxytryptamine2 (5-HT2) receptor agonist, alpha-methyl-5-HT (5-50 microg/kg, i.v.) and the alpha1-adrenoceptor agonist, phenylephrine (2.5-20 microg/kg, i.v.) in conscious Sprague-Dawley rats. The systemic injection of nitroblue tetrazolium elicited pronounced hemodynamic responses that subsided by 10-15 min. Prior to the administration of nitroblue tetrazolium, the injections of alpha-methyl-5-HT and phenylephrine elicited dose-dependent increases in mean arterial blood pressure and mesenteric, renal and hindquarter vascular resistances. After administration of nitroblue tetrazolium, the vasoconstrictor responses elicited by alpha-methyl-5-HT were augmented whereas those elicited by phenylephrine were diminished. These results are consistent with the possibility that nitroblue tetrazolium interacts with the extracellular ligand-binding domains of 5-HT2 receptors and alpha1-adrenoceptor and that this interaction has opposite effects on activities of these G protein coupled receptors.
Owen
Joy R
JR
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389, USA.
Bates
James N
JN
Lewis
Stephen J
SJ
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000578:Amidines / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D003243:Consciousness; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007202:Indicators and Reagents / Q000494:pharmacology; D007275:Injections, Intravenous; D008297:Male; D009580:Nitroblue Tetrazolium / Q000494:pharmacology*; D010656:Phenylephrine / Q000008:administration & dosage / Q000494:pharmacology; D011224:Prazosin / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology; D044348:Receptors, Serotonin, 5-HT2 / Q000502:physiology; D012701:Serotonin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D058826:Serotonin 5-HT2 Receptor Agonists; D012702:Serotonin Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects* / Q000502:physiology
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D000578:Amidines; D007202:Indicators and Reagents; D018340:Receptors, Adrenergic, alpha-1; D044348:Receptors, Serotonin, 5-HT2; D058826:Serotonin 5-HT2 Receptor Agonists; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D010656:Phenylephrine; C042390:alpha-methylserotonin; D009580:Nitroblue Tetrazolium; D012701:Serotonin; C005894:xylamidine; D011224:Prazosin