Peripheral neural mechanism of hypertension in rat models--peripheral sympathetic neurotransmission in hypertension
Masuyama, Y.; Tsuda, K.; Kuchii, M.; Nishio, I.
Journal of Hypertension. Suppl Official Journal of the International Society of Hypertension 4(3): S189-S192
1986
ISSN/ISBN: 0952-1178 PMID: 2431119 Document Number: 272553
To investigate the peripheral neural mechanism of hypertension, norepinephrine release from sympathetic nerve endings was evaluated in various hypertensive rat models. The isolated mesenteric vasculatures were prepared in 7-9-week-old and 20-22-week-old spontaneously hypertensive rats (SHR), DOCA-salt hypertensive rats (DOCA-HT), two-kidney, one clip renal hypertensive rats (2K1C-HT) and their age-matched normotensive controls. The vasoconstrictor responses to exogenous norepinephrine (EN) were significantly enhanced in all hypertensive rat models compared with their age-matched normotensive controls. The pressor responses to electrical nerve stimulation (NS) were greater in SHR than age-matched Wistar-Kyoto (WKY) rats, and were also increased in DOCA-HT. The norepinephrine overflow during NS was significantly greater in young SHR and chronic DOCA-HT than in the normotensive controls. In 2K1C-HT, the norepinephrine overflow by NS was somewhat reduced compared with sham-operated normotensive controls. Inhibition by calcium-antagonist (verapamil) of the pressor responses and norepinephrine overflow during NS was significantly greater in young SHR and chronic DOCA-HT than in their controls. The facilitatory effect on the norepinephrine overflow exerted by the alpha 2-adrenoceptor antagonist, yohimbine, during NS was significantly less in young SHR and chronic DOCA-HT.