Affordable Access

Effect of acute blood volume expansion on cardiac output, plasma dopamine beta-hydroxylase, and renal function in rats with chronic constriction of the ascending aorta.

Authors
  • Wong, J H
  • Baines, A D
Type
Published Article
Journal
Canadian journal of physiology and pharmacology
Publication Date
Apr 01, 1978
Volume
56
Issue
2
Pages
232–240
Identifiers
PMID: 638876
Source
Medline
License
Unknown

Abstract

To examine the effect of raised left atrial pressure (AP) on the relationship of cardiac output to renal function, we constricted the ascending aorta in rats (AC) and 1-6 months later tested their response to acute volume expansion (VE) with blood (2% body weight, iv). Sham-operated (SH) rats were controls. In AC rats heart weight increased 38%, but cardiac output was 47% lower. Statistically significant differences in the initial clearance periods were (AC vs. SH): venous pressure (VP) 8 +/- 2 vs. 3+/- 1 cm H2O; inulin clearance (CIN) 0.61 +/- 0.06 vs. 0.84 +/- 0.04 ml/min; sodium excretion (UNAV) 1.2 +/- 0.2 vs. 2.1 +/- 0.3 muequiv./min. Filtration fraction, fractional UNaV, mean arterial pressure (MAP), and plasma dopamine beta-hydroxylase (DBH) were the same in both groups. After VE, cardiac output increased proportionately more in AC (69% vs. 27%); however, the absolute increases were not different. UNaV increased proportionately more in AC rats, but the absolute increase was less (5.1 vs. 7.5 muequiv./min). Multiple variable regression analysis showed that UNaV correlated with CIN, MAP, and VP, with no difference between AC and SH animals. Cardiovascular-renal relationships were indistinguishable from previous descriptions of dogs and rats with chronic vena caval constriction. Modulation of renal function by left AP was not apparent. In both groups after the peak response to VE, UNaV decreased in association with decreased cardiac output and increased sympathetic nervous activity as indicated by raised DBH levels. After VE, VP remained high in AC but not in SH animals.

Report this publication

Statistics

Seen <100 times