Blood sample analysis and monitoring of hemodynamic parameters and renal function in the conscious rat.

A method is described for chronic instrumentation of the rat with arterial and venous catheters. The technique minimizes the risk of catheter occlusion and damage, and reduces restraint of the animals during the evaluation. In the conscious animal, hemodynamic parameters and renal function can be monitored while substances are injected or blood samples withdrawn.

Atrial natriuretic factor infusion following acute renal ischemia in anesthetized dogs.

Atrial natriuretic factor (ANF) has been shown to be effective in reversing renal functional impairments following renal ischemia. We studied the effects of a nonhypotensive intravenous ANF infusion (100 ng/min x kgBW, 60 min) after 90 min unilateral renal arterial occlusion in anesthetized dogs with an intact contralateral kidney. ANF plasma levels remained unchanged in controls (group 1) and increased in ANF-infused animals (group 2) from 22 +/- 3 to 552 +/- 124 pg/ml. Blood pressure increased in both groups during renal ischemia, but returned to control values in group 2 when ANF infusion was started. Plasma vasopressin did not change in group 1, but increased in group 2 (0.77 +/- 0.29 vs. 1.10 +/- 0.49 pg/ml) after terminating ANF infusion. The postischemic fall in creatinine clearance (CCr), filtration fraction (FF) and renal blood flow (RBF) was prevented by infusion of ANF (CCr: group 1, 0.16 +/- 0.05 vs. group 2, 1.01 +/- 0.25 ml/min x kgBW; FF: group 1, 4.0 +/- 1.6 vs group 2, 14.1 +/- 4.1%; RBF: group 1, 6.0 +/- 1.2 vs. group 2, 9.2 +/- 1.6 ml/min x kgBW); however, the effects were limited to the time of infusion and the postischemic increase in urinary excretion of the proximal tubular enzyme N-acetyl-beta-D-glucosaminidase (NAG; group 1, 317.7 +/- 163.6 vs. group 2, 672.4 +/- 245.7 microU/min x kgBW) was not improved by ANF. Our data suggest that infusion of ANF transiently reverses postischemic renal impairment. However, the failure to demonstrate a sustained postischemic improvement of renal functional parameters and to ameliorate massive NAG excretion casts doubt on the benefit of ANF infusion in preventing cellular damage.

Intact kidney function during contralateral renal artery clamping in dogs.

Experiments were carried out on 32 Nembutal anaesthetized mongrel dogs from both sexes. After 45 min control period unilateral renal ischemia was achieved by clamping the left renal artery for 90 min. In part of the experiments (n = 8) after clamp removal 3 consecutive 45 min periods were performed. The function of the intact right kidney was investigated. Mean arterial pressure (MAP), heart rate (HR), glomerular filtration rate (GFR), urine flow rate (V), fractional excretions of sodium (FENa), potassium (FEK) and chloride (FECl) and plasma levels of atrial natriuretic peptide, dopamine and antidiuretic hormone were evaluated. During ischemia MAP was elevated from 122.5 +/- 3.1 to 140.2 +/- 2.7 mmHg (p < 0.001), HR decreased from 119 +/- 4 to 102.5 +/- 3.9 beats/min (p < 0.01) as compared to the control period. GFR did not change significantly, while all excretory parameters increased: V from 8.7 +/- 1.2 to 14.5 +/- 1.7 microliters/min/gr kidney tissue (p < 0.05); FENa from 2.3 +/- 0.2 to 3.6 +/- 0.3% (p < 0.01); FEK from 40.0 < 3.5 to 51.2 < 2.8% (p < 0.05); FECl from 1.8 < 0.3 to 2.6 < 0.3% (p < 0.05). MAP remained elevated in the first and the second postischemic periods and was paralleled by the sustained increase in FENa and FECl, while FEK remained higher to the end of the experiment. ANP was significantly elevated during ischemia: on 75 min--p < 0.01 and on 105 min.--p < 0.05. AVP and dopamine showed no statistically significant changes during the investigated periods.(ABSTRACT TRUNCATED AT 250 WORDS)