Renal function in patients with untreated acute myocardial infarction

This study provides data on plasma volume (PV), extracellular volume (ECV) and renal function in 8 untreated patients with acute myocardial infarction (AMI). At day 2 and day 10 after AMI, glomerular filtration rate (GFR), urinary excretion rate of water (Vu), sodium clearance (CNa) and lithium clearance (CLi) were used for assessing reabsorption rates of sodium and water in proximal and distal nephron segments. PV and blood pressure at day 2 were not significantly different from values at day 10. Heart rate (HR), weight and ECV at day 2 were significantly increased when compared with values at day 10 (78 vs. 62 pr. min and 17.0 vs. 16.2 1, respectively). Plasma norepinephrine values were slightly elevated at day 2 and day 10. GFR was initially high and decreased from day 2 to day 10 (118 vs. 104 ml min-1) together with CLi and Ck. However, Vu, CNa and fractional excretion rate of sodium increased markedly from day 2 to day 10. The results suggest that sodium and water retention in the initial phase of AMI without left ventricular failure is due to an increase in tubular reabsorption in distal nephron segments mediated by mechanisms other than the sympathetic nervous system.