Influence of desipramine on the contractile responses to noradrenaline, clonidine and to electrical field stimulation in the rat isolated seminal vesicle.

The effect of desipramine (DMI) on the contractile responses to noradrenaline (NA), clonidine and to electrical field stimulation (FS), was studied in the rat isolated seminal vesicle. The aim was to analyse the mechanism of action of DMI in this preparation and compare the results obtained with those already published for other similar preparations, e.g. the guinea-pig seminal vesicle. The results showed that DMI, which on its own had little effect on contractility of rat seminal vesicle, significantly (P less than 0.001) enhanced the Na-induced contractions (by 30-50%), whereas it markedly reduced (by 40%) the contractions produced by clonidine. DMI also enhanced the FS-induced contractions (by about 50%) in the same preparation. The enhancement of the NA-induced responses by DMI can be explained in terms of inhibition of the NA uptake by the preparation, whereas the reduction in clonidine response may be due to blockade of adrenoceptors in the rat seminal vesicle. Other possibilities and mechanisms are also discussed in this and other types of smooth muscle preparations.