Islam M Z, Williams B C, Madhavan K K, Hayes P C, Hadoke P W
Liver Research Unit, Department of Medicine, University of Edinburgh, Edinburgh, Scotland.
Gastroenterology. 2000 Apr;118(4):765-71. doi: 10.1016/s0016-5085(00)70146-6.
BACKGROUND & AIMS: Impaired pressor function in cirrhosis may be specific to certain agonists and vascular territories. This investigation determined whether responses to arginine vasopressin (AVP) and 5-hydroxytryptamine (5-HT) were impaired in hepatic arteries from cirrhotic patients.
Cumulative concentration-response curves were produced for AVP (10(-11) to 3 x 10(-6) mol/L), 5-HT (10(-9) to 3 x 10(-5) mol/L), and potassium chloride (2.5 -120 mmol/L) in hepatic arteries from liver donors (noncirrhotic) and recipients (cirrhotic). The receptor stimulated by AVP was identified using a V(1)-receptor antagonist (dCH(2)Tyr[Me]AVP) and a selective V(2)-receptor agonist (desmopressin [DDAVP]).
Cirrhotic patients had a high heart rate (98 +/- 4 beats/min) and cardiac output (9.87 +/- 0.51 L/min) but low peripheral vascular resistance (711 +/- 35 dyn. s/cm(5)). None of the arteries had a functional endothelium. Maximal contraction (but not sensitivity) to AVP was smaller (P = 0.0002) in hepatic arteries from recipients (34.03% +/- 3.42% KCl) than donors (60.69% +/- 5.56% KCl). 5-HT-mediated contraction was enhanced in recipient hepatic arteries (88.81% +/- 5.43% KCl vs. 71.63% +/- 4. 46% KCl; P = 0.01), but sensitivities were similar (P = 0.20). KCl-mediated contractions were similar (P = 0.87) in both groups. Arteries did not respond to DDAVP, but d(CH(2))(5)Tyr(Me)AVP produced a concentration-dependent rightward shift in the response to AVP.
These results demonstrate a selective impairment of V(1) receptor-mediated contraction in denuded hepatic arteries from cirrhotic patients, suggesting an abnormality within the vascular smooth muscle.
