AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 2 372-R379, Copyright © 1994 by American Physiological Society
Reduced renal sympathoinhibition in response to acute volume expansion in diabetic rats
K. P. Patel and P. L. Zhang
Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha 68198-4575.
To determine whether the renal sympathetic nerve responses to acute volume
expansion (VE) are altered in the diabetic state, we measured the acute
VE-induced renal sympathoinhibition in streptozotocin (STZ)-induced
diabetic rats. Urine flow, sodium excretion, and integrated renal
sympathetic nerve activity were measured before and during an acute graded
VE (with isotonic saline) in anesthetized (Inactin; 0.1 g/kg ip) control
rats (vehicle; n = 7), diabetic rats (Sprague-Dawley rats injected with STZ
65 mg/kg ip 2 wk before experiment; n = 7), and diabetic rats treated with
insulin (2 U/day sc; n = 6). Blood glucose levels were significantly
elevated in the diabetic group (370 +/- 8 mg/dl) compared with the control
group (104 +/- 3 mg/dl). Acute graded VE with isotonic saline produced a
significantly blunted renal sympathoinhibition (50% of control by 10% VE),
diuresis (19% of control by 10% VE), and natriuresis (24% of control by 10%
VE) in the diabetic rats compared with control rats. Treatment with insulin
for 2 wk to restore normoglycemia in diabetic rats (third group; 93 +/- 9
mg/dl) resulted in reversal of the blunted urine flow, sodium excretion,
and renal sympathoinhibition in response to acute VE. However, acute (a few
hours before VE challenge) reduction of hyperglycemia in the diabetic rats
(125 +/- 18 mg/dl) did not correct the blunted renal sympathoinhibition.
The second goal of this study was to determine if enalapril treatment (10
mg/day by mouth) for 2 wk corrects the blunted volume reflex in diabetic
rats. Enalapril did not correct the blunted renal excretory and renal nerve
responses to acute VE in diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)
