Effect of Na+ pump suppression on reactivity of rat trachealis to cooling.
1. This study tests the hypothesis that suppression of Na+ pump would increase the rate of tension development and the magnitude of contraction induced by cooling in airway smooth muscle. 2. Rat tracheal preparations were incubated in ouabain for 8 h and tested hourly for their response. In a representative specimen the rate of tension development increased from the control value of 0.7 mg/s to 5.5 mg/s after 7 h of incubation in ouabain concentration of 4 X 10(-4) mol/L; likewise, the magnitude of contraction increased from the control value of 80 mg to 550 mg. 3. Using ouabain concentrations between 9 X 10(-5) mol/L and 6 X 10(-3) mol/L, the rate of tension development and the magnitude of contraction first increased in a dose-dependent manner up to 8 X 10(-4) mol/L, then declined with higher doses but the responses were still greater than the control values at all concentrations. 4. After 3 h incubation in ouabain at 8 X 10(-4) mol/L, the mean rate of tension development and the mean magnitude of contraction increased to 647% and 578% of the control value, respectively. 5. These results indicate that depression of Na+ pump results in hypersensitivity and hyper-reactivity of the airway smooth muscle to cooling.
Chen
W Y
WY
Department of Physiology, Universidad Central del Caribe School of Medicine, Cayey, Puerto Rico.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003080:Cold Temperature; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000378:metabolism* / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014132:Trachea / Q000378:metabolism / Q000502:physiology
D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase