Effects of adenosine infusion on renal function, plasma ANP and ADH concentrations and central hemodynamics in anesthetized pigs.

1. The effect of high-dose adenosine administration on atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) release is not completely understood, and data concerning the effect of adenosine on renal and systemic hemodynamics in the pig are lacking. Measurements of central hemodynamics, renal blood flow and urine production were made in anesthetized pigs during infusion of adenosine. The relationship between these parameters and the plasma concentrations of ANP, ADH and renal renin production was examined. 2. Adenosine infusion at the rate of 140 mg/kg per minute resulted in a significant decrease in systolic, diastolic and mean arterial blood pressure as well as pulmonary arterial pressure. However, cardiac output and renal blood flow remained unchanged during adenosine infusion. Likewise, heart rate remained unchanged until the end of infusion when it increased significantly, Plasma ANP and ADH concentrations increased significantly within 30 min after adenosine infusion, reaching peak levels at 30 to 60 min. However, despite the significant decrease in arterial blood pressure, renal renin production did not change significantly. 3. The adenosine-induced rise in ANP, which is normally released by atrial stretch, may represent a direct effect of adenosine on the cardiac myocytes. The increase in ADH may be a result of decreased arterial blood pressure triggering stimulatory signals from the aortic arch and carotid body receptors to hypothalamic-pituitary sites of ADH production/release. Urine flow decreased dramatically within 30 min of adenosine infusion. Thus adenosine infusion at the given rate led to marked reduction in systemic and pulmonary arterial pressures without significant change in cardiac output, heart rate and renal blood flow. This was associated with a marked increase in plasma ANP and ADH levels with no significant change in renal renin production despite a marked reduction in arterial blood pressure. 4. Maintenance of renal blood flow despite marked reduction in perfusion pressure suggests that, at high doses, adenosine induces renal vasodilation in pigs as opposed to a combined afferent and efferent vasoconstriction known to occur under different experimental conditions.