Hemodynamic response to vasopressin during V1-receptor antagonism in baroreflex-deficient subjects.
Six quadriplegic subjects and 6 control subjects received high-dose arginine vasopressin (AVP) infusions at rates of 500, 1,000, 2,000, and 4,000 microU.kg-1.min-1 in consecutive 10-min intervals. Six additional quadriplegic subjects received low-dose AVP infusions at rates of 50, 100, 200, 400, and 800 microU.kg-1.min-1. All subjects were studied once with and once without administration of a selective V1-receptor antagonist. During high-dose AVP infusions without V1-receptor blockade, mean arterial pressure (MAP) increased from 80 +/- 4 to 87 +/- 5 mmHg (P < 0.05) in quadriplegic subjects but was unchanged in control subjects. In the presence of V1-receptor blockade, MAP decreased from 75 +/- 4 to 58 +/- 4 mmHg (P < 0.001), and heart rate (HR) increased from 61 +/- 5 to 80 +/- 5 beats/min (P < 0.001) in quadriplegic subjects. In the studies on control subjects, MAP decreased only from 75 +/- 3 to 72 +/- 5 mmHg (P < 0.05), whereas HR increased from 64 +/- 4 to 87 +/- 4 beats/min (P < 0.001). Plasma renin activity (PRA) increased in both quadriplegic and control subjects. The effects of low-dose AVP infusions on MAP, HR, and PRA in quadriplegic subjects were similar to those observed during high-dose infusions. Thus, in the absence of baroreceptor-mediated sympathetic nervous system responses, a vasodilatory effect of AVP that is capable of producing marked reductions in MAP can be demonstrated in the presence of V1-receptor blockade.
Huch
K M
KM
Veterans Affairs Medical Center, Memphis, Tennessee 38104.
Runyan
K R
KR
Wall
B M
BM
Gavras
H
H
Cooke
C R
CR
D000328:Adult; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000494:pharmacology*; D017704:Baroreflex; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007262:Infusions, Intravenous; D010264:Paraplegia / Q000503:physiopathology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology; D011782:Quadriplegia / Q000503:physiopathology*; D012016:Reference Values; D012083:Renin / Q000097:blood; D013119:Spinal Cord Injuries / Q000503:physiopathology*
D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin; D012083:Renin