Supersensitivity of isolated rat vas deferens to dopamine in animals pretreated wit reserpine and haloperidol
Alloza, J.L.; Salva, J.A.
Archivos de Farmacologia y Toxicologia 6(2): 119-130
1980
ISSN/ISBN: 0304-8616 PMID: 7469495 Document Number: 155875
Based on preliminary experiments on isolated rat vas deferens and its response to dopamine, the change due to pretreatment of the animal with reserpine (2.4 mg/kg, i.p. 24 h) and haloperidol (1 mg/kg, i.p. 18 h) was studied. The presence of specific dopaminergic receptors and the absence of antagonism to exogenous norepinephrine by haloperidol (10-8-10-9 M) were previously observed and sensitization to norepinephrine had a maximal concentration of 3 .times. 10-5 to 10-4 M. Reserpinization caused supersensitivity of the postsynaptic receptor, of a nonspecific nature, which caused displacement of the curves to the left, affecting basically the maximal and submaximal effects [P < 0.001) without increases or changes of the affinity through 4 successive registers. The same phenomenon is observed in animals pretreated with haloperidol, but since in normal animals it induces phenomena of sensitization to norepinephrine along with nonspecific supersensitivity, uptake blocking mechanisms may be involved with the amines. The phenomena of supersensitivity correspond to Kalsner type II classification.