Renal response of conscious rats to the simultaneous infusion of glucose and saline.

Conscious male rats received an infusion of glucose in saline (139 mM glucose in 77 mM sodium chloride at 5.2 ml/h) via a tail vein for up to 7 h. A control group of rats received saline alone. Rats of both groups were of similar body weights. Plasma glucose concentration averaged 4.9 +/- 0.4 mmol/l (mean + SEM, n = 5) after 4 h saline infusion and 12.9 +/- 0.2 mmol/l (n = 5; difference, p less than 0.001, paired t-test) after 4 h of combined glucose and saline infusion. Urinary glucose excretion was similar in both groups. Urine flow rate and sodium excretion rate were similar in both groups during the infusions. Calculation of the cumulative changes in sodium balance indicated that both groups of rats returned to sodium balance after about 4 h of infusion and remained so for the subsequent 3 h. Values for plasma protein concentration and plasma osmolality were not significantly different after 4 h of either infusion. Inulin clearance during the 4-6 h period of saline infusion (= 3.40 +/- 0.23 ml/min) was not significantly different to that during the 2-4 h period (= 3.33 +/- 0.20 ml/min). In rats infused with glucose in saline inulin clearance increased significantly during the 4-6 h period compared with that during the 2-4 h period (4.14 +/- 0.32 vs 3.31 +/- 0.32 ml/min, p less than 0.05 paired t-test). Mean arterial blood pressure was similar in the two groups of rats and did not change significantly during the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)