Membrane potential-dependent and-independent tension in the canine tracheal muscle.
We used the double sucrose gap apparatus to describe properties of electromechanical coupling in canine trachealis muscle, during infusion of elevated K+ and 5-hydroxytryptamine (5-HT). With 59 mM K+ and 5-HT, quasi-steady-state relationships of membrane depolarization and tension indicate electromechanical coupling, but for a given increase in tension much smaller membrane depolarizations were seen with 5-HT than with 59 mM K+. Evoked displacements of the membrane potential with anodal or cathodal current caused relaxations or contractions, respectively, and graded displacements resulted in graded tension changes. Reversal of 59 mM K+ membrane depolarization with long anodal current pulses resulted in nearly complete reversal of K+ tension, but reversal of 5-HT membrane depolarization caused tension reversal of only 20 to 40%. Data partially define electromechanical coupling in canine trachealis muscle provide evidence for membrane potential-independent tension with 5-HT at concentrations giving near threshold to maximal 5-HT tension.
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000502:physiology
D012701:Serotonin; D011188:Potassium