title: Inhibitory action on alpha-human atrial natriuretic polypeptide on vascular adrenergic neurotransmission is attenuated in spontaneously hypertensive rats.
abstract: The purpose of the present study is twofold, firstly to investigate the effects of alpha-human atrial natriuretic polypeptide (alpha-hANP) on norepinephrine overflow from sympathetic nerve endings, and secondly to compare vascular responsiveness in perfused mesenteric preparations in spontaneously hypertensive rats (SHR, Okamoto and Aoki, 7-9 weeks old) and a cohort of Wistar Kyoto rats (WKY). In preliminary studies using normotensive Wistar rats, the pressor responses to electrical nerve stimulation or exogenous norepinephrine application were inhibited by alpha-hANP. Norepinephrine overflow was also suppressed by alpha-hANP, during nerve stimulation. The pressor responses and norepinephrine overflow during nerve stimulation were significantly greater in SHR than in WKY rats. The inhibitory effect of alpha-hANP on these responses was reduced in SHR. These results indicate that alpha-hANP could affect both pre- and post-synaptic sites of the resistance vessels. Further, the reduced inhibition of pressor responses and norepinephrine overflow by alpha-hANP in SHR suggests an insufficient regulation of adrenergic transmission by alpha-hANP in hypertension.
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000294:innervation* / Q000378:metabolism; D009433:Neural Inhibition; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D009320:Atrial Natriuretic Factor; D009638:Norepinephrine