Role of autonomic function in the antihypertensive effect of vasopressin withdrawal in spontaneous hypertension.
The importance of the autonomic nervous system (ANS) in the withdrawal-induced antihypertensive phenomenon (WAP) to arginine-vasopressin (AVP) in the spontaneously hypertensive rat (SHR) was investigated by studying the response to AVP infusion and withdrawal in the presence and absence of ganglionic blockade. In the absence of autonomic blockade, AVP infusion (20 ng/kg/min for 3 h) produced similar pressor responses initially in the SHR (45 +/- 2.0 mm Hg) and in the Wistar-Kyoto rat (WKY) (43 +/- 3.3 mm Hg). The pressor response was not well-maintained in SHR, falling to 21 +/- 0.8 mm Hg above preinfusion basal values by the end of the 3-h infusion. Cessation of the infusion was associated with a dramatic decrease in pressure below basal levels in the SHR: 3 h after the withdrawal of AVP, pressure had dropped from the preinfusion level of 171 +/- 4.0 mm Hg to 141 +/- 4.5 mm Hg, whereas pressure had returned to control levels in the WKY. In the presence of the ganglionic blocking agent, the changes in pressure both during and after the AVP infusion were similar in SHR and WKY: 3 h after the withdrawal of the AVP infusion, pressure was only slightly reduced below preinfusion levels in SHR (from 112 +/- 4.6 to 100 +/- 2.9 mm Hg) and WKY (from 76 +/- 2.7 to 75 +/- 2.6 mm Hg). The results suggest that an intact ANS is important to the expression of the WAP in the SHR, in that the WAP may require a withdrawal of sympathetic tone.
Chiu
E K
EK
Department of Pharmacology, University of Saskatchewan, Saskatoon, Canada.
McNeill
J R
JR
D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D005724:Ganglia / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D007022:Hypotension / Q000139:chemically induced* / Q000503:physiopathology; D007262:Infusions, Intravenous; D008297:Male; D010425:Pentolinium Tartrate / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013375:Substance Withdrawal Syndrome
D001127:Arginine Vasopressin; D010425:Pentolinium Tartrate