Effects of increasing osmolality on rat ileal smooth muscle.
The effects of changing bathing medium osmolality on tension generation in smooth muscle were studied on potassium-depolarized segments of rat ileum. Increasing the tonicity of the medium evokes a transient relaxation of the smooth muscle; restoration of isotonicity evokes a transient contraction of similar amplitude and time course. While immersed in hypertonic media of less than 1.3 times normal tonicity, the smooth muscle slowly increases its isometric tension; in media of nearly twice normal tonicity, the smooth muscle loses tension. All of these effects occur whether the medium is made hypertonic with added NaCl or sucrose.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007082:Ileum / Q000502:physiology; D066298:In Vitro Techniques; D009129:Muscle Tonus / Q000187:drug effects*; D009130:Muscle, Smooth / Q000502:physiology*; D009994:Osmolar Concentration; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*
D012965:Sodium Chloride; D012964:Sodium; D002118:Calcium