Detrusor smooth muscle in rats with alloxan-induced diabetes.

Following five weeks of alloxan-induced diabetes, female rats were killed and the urinary bladder was used either for organ bath experiments, collagen determination or electron microscopy. Mean bladder weight increased from 70 +/- 3 (SE, n = 8) for controls to 131 +/- 7 mg. (n = 9) for the diabetic rats. Collagen concentration decreased from 104 +/- 5 (n = 8) to 69 +/- 4 (n = 9) micrograms/mg. but due to the weight gain total bladder collagen increased from 7.4 +/- 0.6 to 8.9 +/- 0.3 mg. Electron microscopy indicated an increase in mean cross-sectional area of the detrusor smooth muscle cells from 8.1 +/- 0.5 (n = 132) to 19 +/- 0.9 (n = 144) mu 2. Despite these changes the bladders from diabetic animals and the controls had similar characteristics with regard to nerve mediated frequency-response relations, atropine resistance, responses to alpha-agonists and high-K+ solution. No functional neurogenic lesion and no impairment of smooth muscle cell contractility could thus be detected, and it is proposed that the bladder hypertrophy in the diabetic animals is due to a physiological adaptation to the four-fold increase in urinary production.