RESUMO
SP produces two different muscular responses in the isolated vas deferens of the rat. 1) A myotropic, post-synaptic effect that results from stimulation of one subtype of SP receptor, located on the membrane of the smooth muscle (NK-3 receptor). 2) A neurogenic effect at the pre-synaptic level that results from stimulation of another subtype of SP receptor, located on the nerve terminals (NK-1 receptor).
Assuntos
Receptores de Neurotransmissores/metabolismo , Substância P/farmacologia , Ducto Deferente/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Estimulação Elétrica , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Músculo Liso/inervação , Músculo Liso/fisiologia , Neurônios/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Receptores da Neurocinina-1 , Sinapses/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacosRESUMO
The response of post-synaptic neurokinin receptors to SP were not changed by pirenzepine or N-methyl-scopolamine. Atropine led to a slight increase in the EC50 of SP for its post-synaptic neurokinin (NK-A) receptor. In the presence of neostigmine no changes in the Emax and EC50 values of SP for its post- and pre-synaptic receptor site were observed. Only the muscarinic receptor site were observed. Only the muscarinic receptor antagonists, atropine and NMS, elicited statistically significant increases in the Emax of SP at its presynaptic receptor (NK-A). Addition of 7.4-740 nM SP resulted in a decrease in the EC50 and Emax values of ACh for its post-synaptic muscarinic receptor (M1). Conversely, 740 nM SP produced an increase in the EC50 and Emax values of ACh at its pre-synaptic muscarinic receptor (M2). Concentrations of 7.4 and 74 nM SP did not produce statistically significant changes in the Emax of ACh for its pre-synaptic M2 receptor.
