title: Inhibition of norepinephrine release by presynaptic alpha 2-adrenoceptors in mesenteric vasculature preparations from chronic DOCA-salt hypertensive rats.
abstract: This study investigated norepinephrine release during electrical nerve stimulation and inhibitory characteristics of presynaptic alpha 2-adrenoceptors in perfused mesenteric vasculature from deoxycorticosterone acetate (DOCA)-salt hypertensive rats (7-8 weeks after surgery). Electrical stimulation of sympathetic innervation caused a significantly greater release of endogenous norepinephrine into the mesenteric vasculature of DOCA-salt hypertensive rats than in age-matched normotensive controls. Pressor responses to electrical nerve stimulation were also enhanced in DOCA-salt hypertension. Yohimbine, a potent alpha 2-adrenoceptor blocking agent, potentiated the stimulation-evoked release of norepinephrine into the vasculature in normotensive rats. This effect was blunted in DOCA-salt hypertension. These results suggest that increased norepinephrine release from the sympathetic nerve endings in DOCA-salt hypertension might partly reflect an impaired presynaptic alpha 2-adrenoceptor-mediated inhibition, which could enhance vascular sympathetic tone in this model of hypertension.
authors.affiliation: Department of Medicine, Wakayama Medical College, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tsuda
authors.forename: S
authors.initials: S
authors.lastname: Tsuda
authors.forename: I
authors.initials: I
authors.lastname: Nishio
authors.forename: Y
authors.initials: Y
authors.lastname: Masuyama
mesh_terms: D000818:Animals; D003900:Desoxycorticosterone; D004558:Electric Stimulation; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008638:Mesenteric Arteries / Q000502:physiology*; D008642:Mesenteric Veins / Q000503:physiopathology*; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D012965:Sodium Chloride; D013569:Synapses / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D009638:Norepinephrine