Infusion of atrial natriuretic factor in conscious rats initially decreased mean arterial pressure and cardiac output, but autoregulatory phenomena returned cardiac output to control levels by day 5.
Does atrial natriuretic factor infusion alter systemic hemodynamics in conscious normotensive rats?
Pathophysiological elevations in plasma ANF significantly alter systemic hemodynamics initially via decreased cardiac output, but autoregulatory mechanisms normalize CO during chronic elevation.
The present study was designed to examine acute (2 h) and chronic (5 day) effects of pathophysiological elevations of plasma atrial natriuretic factor (ANF) in conscious normotensive rats. Acute infusion of ANF (100 ng.kg-1.min-1; n = 15) resulted in a decrease in mean arterial pressure (MAP) of 5 +/- 3 mmHg, which was associated with a 23 +/- 4% decrease in cardiac output (CO) and a 27 +/- 6% increase in total peripheral resistance (TPR). Hematocrit increased from 41.9 +/- 0.7 to 46.0 +/- 0.6%, which is suggestive of vascular volume contraction. Chronic infusion of ANF (n = 9) produced a significant fall in MAP from a control value of 114 +/- 2 to 100 +/- 3 and 99 +/- 2 mmHg on days 1 and 5, respectively. CO decreased significantly (27 +/- 2%) and TPR increased (21 +/- 5%) on day 1; neither variable was significantly different from control on day 5. Plasma immunoreactive ANF levels were significantly elevated during acute (791 +/- 76 pg/ml) and chronic (626 +/- 202 pg/ml) ANF infusion compared with control values of approximately 100 pg/ml. The results indicate that elevations in plasma ANF within the pathophysiological range can significantly alter systemic hemodynamics, initially mediated by a decrease in CO. Autoregulatory phenomena may counteract these hemodynamic effects, returning CO to control levels and reducing TPR when the elevations in plasma ANF are chronically sustained.
Harrison‐Bernard et al. (1991) studied conscious normotensive rats (n=24). Atrial natriuretic factor (ANF) vs. control was evaluated on Systemic hemodynamics (mean arterial pressure, cardiac output, total peripheral resistance). Infusion of atrial natriuretic factor in conscious rats initially decreased mean arterial pressure and cardiac output, but autoregulatory phenomena returned cardiac output to control levels by day 5.