Enhancement of Ca-contractions by catecholamines and temperature dependency in the depolarized teania coli of the guinea-pig.

摘要: Guinea-pig taenia colt suspended in a depolarizing solution without Ca responded to by contraction. The effects of adrenaline, noradrenaline and isoprenaline on the contractile response were investigated at 20°C 37°C. Contractile was not significantly affected adrenaline noradrenaline, but reduced At 20°C, all three catecholamines inhibited Ca-contraction. potency producing inhibition isoprenaline, same sequence as related beta-receptor mediated responses. Treatment with blocking agent markedly or abolished inhibitory effects, consequently Ca-contraction enhanced an alpha-receptor increased so that 37°C well 20°C. order after blockade again noradrenaline. It concluded stimulatory effect is activation activation. After 37°C, applied caused further development tension. resembles slow component ACh-induced contraction, regarding time course susceptibility removal from extracellular medium. Adrenaline extent before frequent exposures ACh deplete cell-bound Ca. These findings suggest enhancement dependent permeation ions across cell membrane.