Normal mechanicalactivityof catcolonicmusclesegments was abolished during incubation incalcium-freesolution. Incalcium-freesolution, contractions could be induced by direct electrical stimulation or by depolarization with high potassium. In high potassiumcalcium-freesolution, carbachol also induced an additionalcontractileresponse due to muscarinicreceptoroccupation. It is concluded that incolonicsmooth muscle, depolarizationmediated, as well asreceptormediated, release of intracellularcalciumoccurs.
Mangel AW. Voltage and receptor mediated contractile activity of colonic smooth muscle in calcium free solution. Eur J Pharmacol. 1984 Jun 15;102(1):165-8.
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