Pharmacological zero for electromagnetic renal blood flow measurement.

Measurement of blood flow in chronically instrumented laboratory animals using electromagnetic flow probes depends on a reference "zero flow" value. The latter is usually obtained by mechanical vessel occlusion. We tested an alternative method: a bolus of angiotensin II was injected in the abdominal aorta resulting in an immediate decrease of renal blood flow. Diastolic blood flow at this stage appeared to be identical to the zero level obtained by mechanical occlusion. Thus, pharmacological interruption of renal blood flow may serve as a zero reference in the dog.