Spontaneous rhythmicity induced by glucose removal in the guinea-pig tracheal smooth muscle

Guinea-pig tracheal smooth muscle was mechanically quiescent in the normal Krebs-Henseleit solution, but rhythmic contraction appeared after removal of glucose from the solution with or without carbachol and was accompanied by a gradual decrease in the resting tension. There was no significant difference in lag time required for appearance of the rhythmicity and % decrease of the tension between glucose removal in the absence and presence of carbachol. Induction of the rhythmicity was limited by hypoxia plus glucose removal, without and with carbachol. The rhythmic contraction produced by glucose removal was low in amplitude and disappeared within one hour, whereas, when a low dose of glucose (0.1-0.2 mM) was periodically applied after glucose removal, the rhythmic contraction was higher in amplitude and continued for over 5 hr. The rhythmicity elicited by glucose removal in combination with an adequate supply of glucose was abolished by addition of glucose (0.22-0.25 mM), ATP (1.8 mM), or pyruvate (0.9 mM), accompanied by restoration of the tension to a certain degree, but not by 3-O-methyl glucoside (11.5 mM). The results suggest that the rhythmicity may be masked in normal metabolic states but unmasked in metabolically deficient states in the guinea-pig tracheal smooth muscle.