Chronic ethanol administration affects many organ systems, including sexual organs. One of these organs is the vas deferens whose contractility can also be altered by selective serotonin re-uptake inhibitors (SSRIs). The aim of the present study, is to evaluate whether paroxetine (PX), a SSRI, can modify the contractile responses of isolated vas deferens obtained from rats chronically treated with ethanol to the contractile agents, potassium chloride (KCl) and adenosine triphosphate (ATP). For 21 days, alcohol was applied with a modified liquid diet to sexually mature male Sprague-Dawley rats (200-240 g). The vas deferens of the rats were excised at the end of day 21 and suspended in the organ baths by classical pharmacological methods. The responses to contractile agents tested were decreased by chronic ethanol treatment in all groups compared to their untreated matches. pX (10(-7) and 10(-6) M) potentiated the contractions to KCl (20-180 mM) and ATP (10(-6) to 10(-3) M) in epididymal portion but its higher concentrations (10(-5) and 10(-4) M) inhibited the responses, both in the control and chronically ethanol treated rat groups. Prazosin (PR), an alpha adrenergic receptor blocker, could not inhibit PX-induced potentiation in lower concentrations of KCI but could inhibit the potentiation occurred at higher concentrations of KCI in epididymal portion both in the control and chronically ethanol treated rat groups. PR also inhibited PX-induced potentiation on the responses to ATP in epididymal portion both in the control and chronically ethanol treated rat groups. In conclusion, all the results obtained in this study, suggest that chronic ethanol treatment decreased the contractility of vas deferens but did not alter the action pattern of PX on responses to KCI and ATP in rat vas deferens. On the other hand, the potentiation of responses to contractile agents induced by PX can be partially considered as the result of inhibition of noradrenaline re-uptake. (C) 2003 Elsevier B.V. All rights reserved.