Dysfunction of supramedullary alpha-adrenergic mechanisms following sino-aortic denervation in Kyoto Wistar rats.
Central alpha-adrenergic mechanisms of blood pressure regulation were investigated by injecting norepinephrine or bradykinin into the carotid input of the cross-circulated head preparations of normotensive Wistar Kyoto rats (WKY). Rats were divided into three groups: sham-operated (sham), carotid sinuses denervated (SD) and carotid sinuses and aortic nerves debuffered (SAD). Norepinephrine, 5 micrograms, produced vasodepression in all rats, accompanied by corresponding decreases in sympathetic nerve activity recorded in some rats. Magnitude of vasodepression was largest in SAD rats. In sham rats, bradykinin, 1 micrograms, produced a biphasic response: initial vasodepression followed by a sustained pressor phase. This was accompanied by corresponding changes in peripheral sympathetic nerve activity recorded in some rats. In both SAD and SD rats bradykinin-induced vasodepression was abolished, while the magnitude of the pressor phase became more prominent. The increase in the pressor phase was greater in SAD than in SD rats. In similar studies of spontaneously hypertensive rats (SHR), responses to both alpha-adrenergic agonist and bradykinin are augmented, suggesting a dysfunction of hypothalamic alpha-adrenergic mechanisms. Since in the present study it has been shown that sino-aortic denervation produces effects similar to those seen in SHR, dysfunction of buffer nerves may account for the deficient central alpha-adrenergic mechanisms in SHR.
D000818:Animals; D001011:Aorta / Q000294:innervation*; D001794:Blood Pressure / Q000187:drug effects; D001920:Bradykinin / Q000494:pharmacology; D002346:Carotid Sinus / Q000294:innervation*; D003714:Denervation; D006339:Heart Rate; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D001920:Bradykinin; D009638:Norepinephrine