[Diabetes mellitus reduces the expression of SK3 in rat cavernous tissues].

Objective: SK3, one of the small conductance calcium-activated potassium channels, is the key substance of the endothelium-derived hyperpolarizing factor (EDHF) passway. This study aimed to investigate the expression of SK3 in the cavernous tissue of rats with diabetes mellitus (DM).

Methods: Twenty-six DM models were made by injection of streptozocin (STZ) out of 50 male Sprague-Dawley rats, and another 15 that failed to be modeled were included in an STZ group. Ten healthy male rats were taken as blank controls. Eight weeks later, the penile erectile function of the rats was detected by injection of apomorphine (APO) at 80 microg/kg, and the expression of SK3 in the cavernous tissue was determined by RT-PCR and Western blot.

Results: Penile erection was observed in 14 (54%) of the 26 DM rat models and in all the rats of the STZ and blank control groups. Both the mRNA and protein expressions of SK3 were significantly lower in the DM (0.50 +/- 0.09 and 0.65 +/- 0.06) than in the STZ (1.15 +/- 0.03 and 1.28 +/- 0.04) and blank control groups (1.21 +/- 0.04 and 1.34 +/- 0.05) (P < 0.05). There were no significant differences between the STZ and blank control groups in either penile erection or mRNA and protein expressions of SK3 (P > 0.05).

Conclusion: Diabetes mellitus can significantly reduce erectile function in rats, which may be related to the decreased expression of SK3 in the corpus cavernosum.