Pertussis toxin attenuates angiotensin II but not beta-adrenoceptor facilitation of noradrenaline release from rat kidney cortex.
1. Angiotensin II (AII; 0.01 and 0.1 mumols/L), angiotensin I (AI, 0.1 mumols/L) and the beta-adrenoceptor agonist isoprenaline (0.1 mumols/L) all facilitated the stimulation-induced outflow of radioactivity from slices of rat kidney cortex incubated in [3H]-noradrenaline. 2. Treatment of rats with pertussis toxin (25 and 50 micrograms/kg i.v.) to inactivate G-proteins attenuated the facilitation caused by AII and AI, but not that caused by isoprenaline. 3. The hypothesis that isoprenaline enhances noradrenaline release by generating AII to activate facilitatory prejunctional AII receptors is not supported by the present study. The hypothesis predicts that pertussis toxin, by inactivating the G-proteins associated with AII receptors, should have inhibited the facilitatory effect of isoprenaline. This did not occur.
Murphy
T V
TV
Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia.
Majewski
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D000803:Angiotensin I / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000804:Angiotensin II / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D019204:GTP-Binding Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D037342:Pertussis Toxin; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D011943:Receptors, Adrenergic, beta; D010566:Virulence Factors, Bordetella; D000804:Angiotensin II; D000803:Angiotensin I; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D007545:Isoproterenol; D009638:Norepinephrine