Validation of transonic small animal flowmeter for measurement of cardiac output and regional blood flow in the rat.

The objective of the present study was to validate a transonic flowmeter system with two probes (model 3SS for cardiac output (CO) and 1RB for organ flows) in Sprague-Dawley (SD) rats first by measuring blood flow through pump-infused isolated renal artery and ascending aorta, and then through measurements of CO and renal, mesenteric, and hindquarter blood flow (RBF, MBF, HBF) in vivo. We measured in vivo baseline flow and changes in flow induced by dopamine and propranolol for CO, prostaglandin E2 (PGE2), and angiotensin II (AII) for RBF and pentobarbital sodium for MBF and HBF. Correlations between meter and pump flow were linear (r = 0.999, p < 0.001) with close agreement both in ascending aorta and renal artery flow measurements. The baseline values were 15 +/- 0.7 ml/100 g/min for CO, 4 +/- 0.1 ml/100 g/min for RBF, 7 +/- 0.3 ml/100 g/min for MBF, and 6 +/- 0.3 ml/100 g/min for HBF, respectively. The system reliably detected increase and/or decrease in CO and regional blood flows. The transonic flowmeter system is accurate, highly reproducible, and compatible with other established techniques for measuring CO and regional blood flows in the rat.