Central sympathetic stimulation produced by saline application into the nucleus tractus solitarii area of conscious rats.
Hypertonic saline 4% was microinjected into the area of the nucleus tractus solitarii (NTS) of conscious rats. The experiments were designed to explore the systemic hormonal responses and the contribution of various hormones to the hypertensive effect elicited by this procedure. A mean blood pressure rise to 155 +/- 3 mmHg (as compared to 119 +/- 2 in rats receiving the same volume of equiosmolar dextrose solution, P less than 0.05) was accompanied by significant rises in plasma norepinephrine (0.556 +/- 0.128 ng/ml) and epinephrine (0.970 +/- 0.287 ng/ml) as compared to control rats receiving dextrose or control rats having only the cannula implanted, without microinjection. There was no significant change in plasma renin activity or plasma vasopressin levels, and the blood pressure rise could not be prevented or reversed by an angiotensin-converting enzyme inhibitor. The data are consistent with the hypothesis that the hypertensive response to this procedure is mainly due to an acute stimulation of central sympathetic neurons.
Vlahakos
D
D
Department of Medicine, Boston City Hospital, MA.
Gavras
H
H
D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D002395:Catecholamines / Q000097:blood; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology*
D002395:Catecholamines; D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin; D012965:Sodium Chloride