Se identificó el subtipo alfa1 adrenoceptores como mediador de la respuesta secretoria en la glándula submaxilar de la rata, basándose en el empleo de diferentes dosis de antagonistas adrenérgicos selectivos alfa1 (prazosín), alfa2 (yohimbina) y no selectivo (fenatolamina) ante la acción del neurotransmisor, la noradrenalina. Los parámetros determinados tanto en glándulas normales como crónicamente desnervadas fueron: a) desplazamientos de las curvas dosis-respuesta; b) dosis efectiva 20 microlitros (DE20 ,ul) y c) determinación del pA2. El hallazgo de la curva dosis-respuesta al agonista beta, isoproterenol, no se vióalterada por la presencia del prazosín, apoya la hipótesis de que el subtipo alfa1 de receptores adrenérgicos, media la respuesta salival simpática. / In the present report, the identification of the subtype alpha-adrenoceptor which mediates the secretory responses in the rat's submaxilary gland, was estudied. For this purpose, the secretory responses to the sympathetic neurotransmitter, noradrenaline, were determined in the presence of different doses of selective alfa1 adrenergic antagonists (prazosin); in the presence of alfa2 selective adrenergic antagonists (yohimbine) and after administration of a non selective adrenergic antagonist (phentolamine). In both, normally innervated as well as in chronic sympathetically denervated glands, the parameters studied were the following: 1) shift of the dose-response curves; 2) DE20 ,ul and 3) pA2 determination. From the results obtained it is concluded that the alfa1 subtype of adrenoceptors mediates the sympathetic secretory responses in the submaxillary gland. This interpretation is further supported by the finding that the response to the beta agonist, isoproterenol, were unchaged after administration of different doses of prazosin.