RESUMO
Diltiazem, a calcium channel blocker was studied to observe its effects on the acetylcholine contractile responses of isolated frog rectus abdominis muscle. This response was modified in a dual manner i.e., initial potentiation, followed by inhibition. Diltiazem may not have anticholinesterase like mechanism, as it potentiated the responses to both acetylcholine and succinylcholine. Rectus muscle preparation, incubated in calcium free frog Ringer, showed dose dependent inhibition of acetylcholine contractile responses by diltiazem. The study suggests that diltiazem inhibits calcium ion influx across receptor operated calcium channels and may also inhibit calcium ion release from intracellular structures.
Assuntos
Cálcio/metabolismo , Diltiazem/farmacologia , Reto do Abdome/efeitos dos fármacos , Acetilcolina/antagonistas & inibidores , Acetilcolina/farmacologia , Animais , Anuros , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio/fisiologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Técnicas In Vitro , Contração Muscular/efeitos dos fármacos , Reto do Abdome/metabolismo , Succinilcolina/antagonistas & inibidores , Succinilcolina/farmacologiaRESUMO
Spasmogenic action of histamine, 2-(2-aminoethyl) pyridine (H1 receptor agonist) and 4 methyl-histamine (H2 receptor agonist), have been studied in guinea pig isolated urinary bladder in the presence of mepyramine (H1 antagonist) and metiamide (H2 antagonist) to identify the presence of H1 and H2 receptors. The study suggested the presence of H1 as well as H2 receptors in this preparation.
