Decreased total venous capacity in Goldblatt hypertensive rats.

Mean circulatory filling pressure (MCFP) and total blood volume (BV) were determined in conscious rats during the early, intermediate, and chronic phases of one-kidney, one-clip Goldblatt hypertension. MCFP was determined from arterial and venous plateau pressures during brief circulatory arrest, which was accomplished by inflating an indwelling right atrial balloon. BV as determined from plasma volume (125I-albumin), arterial hematocrit, and the F-cells factor. As compared with one-kidney sham groups, MCFP was significantly increased in one-kidney, one-clip Goldblatt hypertensive groups at 3, 14, and 28 days postclipping, whereas no significant differences in BV between hypertensive and normotensive groups were observed at any of these time periods. Total vascular compliance, estimated by measuring MCFP before and immediately after rapid BV changes, was significantly decreased in all one-kidney, one-clip Goldblatt hypertensive groups. These results indicate that venous constriction was increased and whole-body venous capacity was decreased in all three phases of one-kidney, one-clip Goldblatt hypertension studied. The mechanism leading to increased venous constriction in one-kidney, one-clip Goldblatt hypertension remains to be elucidated.