Effects of haemorrhage and volume expansion on portal-systemic collateral vascular resistance in conscious portal hypertensive rats.
1. In order to study the acute effects of blood volume changes on the vascular resistance of portal-systemic collaterals (collateral vascular resistance), a model of total portal vein occlusion with 100% portal-systemic shunts was developed in the rat. In this model, we determined the haemodynamic effects of haemorrhage (1.8 ml/100 g body weight) or intravenous infusion of a volume expander (1.8 ml/100 g body weight). Cardiac output and regional blood flows were measured by the radioactive microsphere method. 2. Haemorrhage significantly reduced arterial pressure from 108 +/- 4 to 92 +/- 4 mmHg (mean +/- SEM), cardiac output from 56 +/- 4 to 24 +/- 2 ml min-1 100 g-1 body weight, portal pressure from 15.1 +/- 1.5 to 10.0 +/- 1.4 mmHg and portal tributary blood flow from 19.9 +/- 2.3 to 8.3 +/- 1.4 ml/min. Consequently, collateral vascular resistance significantly increased from 6.6 +/- 0.9 x 10(3) to 11.1 +/- 2.0 x 10(3) kPa 1(-1) s. 3. Volume expansion reduced arterial pressure from 98 +/- 3 to 90 +/- 3 mmHg, and significantly increased cardiac output from 43 +/- 3 to 55 +/- 3 ml min-1 100 g-1 body weight, portal pressure from 13.9 +/- 0.7 to 16.5 +/- 0.8 mmHg and portal tributary blood flow from 16.4 +/- 1.3 to 28.2 +/- 3.2 ml/min. Consequently, collateral vascular resistance significantly decreased from 7.0 +/- 0.5 x 10(3) to 4.9 +/- 0.4 x 10(3) kPa l-1 s. 4. This study shows that in rats with portal hypertension, portal-systemic collateral vascular resistance is modified by alterations in blood volume.
Koshy
A
A
Unité de Recherches de Physiopathologie Hépatique (INSERM U-24), Hôpital Beaujon, Clichy, France.
Sekiyama
T
T
Cereda
J M
JM
Hadengue
A
A
Girod
C
C
Lebrec
D
D
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001810:Blood Volume / Q000502:physiology*; D003097:Collateral Circulation / Q000502:physiology*; D004195:Disease Models, Animal; D006339:Heart Rate / Q000502:physiology; D006470:Hemorrhage; D006975:Hypertension, Portal / Q000503:physiopathology*; D008026:Ligation; D008297:Male; D011168:Portal System / Q000502:physiology*; D011169:Portal Vein / Q000601:surgery; D051381:Rats; D011919:Rats, Inbred Strains; D014655:Vascular Resistance / Q000502:physiology*