Inhibitory effects of Diazepam in rat Vas Deferens: role of Calcium

ABSTRACT

Diazepam and Ro5-4864 effects on noradrenaline-induced rat vas deferend contractions were studied. We investigated whether central or peripheral type benzodiazepine receptors were involved, by studying the effects of the selective central or peripheral benzodiazepine receptor antagonists, flumazenil (Ro 151788) or PK 11195 respectively. Diazepam interactions with GABA, adenosine, theophylline, and hypercalcic medium (3.5mM) were studied. Also, we investigate diazepam effect on KC1 depolarized vas deferens. Results showed that diazepam (10(-4) to 1.7x10(-4) M)) and Ro 5-4864 (10(-5) to 5.5x10(-5)M) inhibited NA-induced vas deferens contractions and that neither flumazenil nor PK 11195 antagonized diazepam or Ro 5-4864 inhibitory effects respectively. GABA, adenosine and theophylline did not modify neither NA vas deferens response nor diazepam inhibitory action. Diazepam effect was significantly reduced in an 3.5 mM calcium medium and KC1 vas deferense was inhibited by diazepam 1.3x10(-5) and 1.3 x 10(-4) M. It is concluded that in rat vas deferens diazepam effect seems to be related with calcium mobilization.