Augmented responsiveness to sympathetic nerve stimulation of isolated vas deferens of diabetic rats

The responsiveness to nerve stimulation in the prostatic end of the rat vas deferens and the influence thereupon of streptozotocin-induced diabetes were examined. The rat vas deferens showed a biphasic contractile response to field stimulation: a rapid twitch contraction followed by a slower tonic contraction. Diabetic rats, at 8 and 12 weeks after induction of diabetes, showed a significant increase in the tonic response when compared with age-matched control rats. The twitch response was slightly increased in 12 week diabetic rats at low frequencies of stimulation. Treatment with insulin reversed the augmented response to nerve stimulation found in diabetic rats. The tonic phase in control rats was inhibited by prazosin (73.5%), and by alpha,beta-methylene ATP (34.6%). In diabetic rats at 12 weeks, about 30% of the tonic response was inhibited by prazosin; in the presence of prazosin, the response was still significantly augmented in comparison with that in control rats. In contrast, the tonic response in the presence of alpha,beta-methylene ATP was the same in diabetic and control rats. These results indicate that diabetes induces an increase in the purinergic component of the response to sympathetic nerve stimulation of the rat vas deferens.