Central G-alpha subunit protein-mediated control of cardiovascular function, urine output, and vasopressin secretion in conscious Sprague-Dawley rats.
The role(s) of central Galpha-proteins in the regulation of cardiovascular and renal function is unknown. We examined how inhibition/downregulation of central Galphai/Galphao, Galphaz or Galphaq proteins altered the characteristic cardiovascular (depressor), renal excretory (diuretic), and plasma AVP (inhibitory) responses to intracerebroventricular injection of nociceptin/orphanin FQ (N/OFQ) in rats. Before investigation, rats were pretreated intracerebroventricularly with saline vehicle (5 microl, 48 h, n=6), pertussis toxin (PTX; 48-h, 1 microg, n=6), or Galphaz, Galphaq, or scrambled oligodeoxynucleotide (ODN) (25 microg, 24 h, n=6 per group). On the study day, intracerebroventricular N/OFQ (5.5 nmol) or vehicle (5 microl) was injected into pretreated conscious rats. Mean arterial pressure (MAP) and heart rate (HR) were recorded, and urine was collected for 90 min. In vehicle or scrambled ODN groups, intracerebroventricular N/OFQ decreased MAP and HR and produced water diuresis (sensitive to UFP-101, N/OFQ receptor antagonist). The hypotension and bradycardia, but not diuresis, to N/OFQ were abolished in PTX-pretreated rats. In contrast, intracerebroventricular ODN pretreatment markedly blunted (Galphaz) or augmented (Galphaq) the diuresis to intracerebroventricular N/OFQ. In separate studies, the action of central N/OFQ to decrease plasma AVP levels in naïve water-restricted rats was differentially altered by intracerebroventricular Galphaz ODN (blunted) and Galphaq ODN (augmented) pretreatment. These studies demonstrate central Galphai/Galphao activity mediates intracerebroventricular N/OFQ's cardiovascular depressor function. Alternatively, central Galphaz (inhibitory) and Galphaq (stimulatory) activity differentially modulates AVP release to control the pattern of diuresis to intracerebroventricular N/OFQ. These findings highlight the novel selective central Galpha-subunit protein-mediated control of cardiovascular vs. renal excretory function.
Wainford
Richard D
RD
Department of Pharmacology, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112, USA. rwainf@lsuhsc.edu
Kurtz
Kristine
K
Kapusta
Daniel R
DR
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D001794:Blood Pressure; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D004231:Diuresis / Q000187:drug effects; D044385:GTP-Binding Protein alpha Subunits / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D006339:Heart Rate; D007276:Injections, Intraventricular; D008297:Male; D009292:Narcotic Antagonists; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage; D018847:Opioid Peptides / Q000008:administration & dosage / Q000378:metabolism*; D037342:Pertussis Toxin / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000378:metabolism; D013997:Time Factors; D014554:Urination / Q000187:drug effects; D014868:Water Deprivation; D000094942:Nociceptin Receptor; D000097629:Nociceptin
D001127:Arginine Vasopressin; D044385:GTP-Binding Protein alpha Subunits; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D009292:Narcotic Antagonists; D009838:Oligodeoxyribonucleotides; D018847:Opioid Peptides; D037342:Pertussis Toxin; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C479838:(Nphe(1),Arg(14),Lys(15))N-OFQ NH(2); C490963:Gnaz protein, rat; C000722285:Oprl1 protein, rat