Bronchial smooth muscle energetics: effect of iodoacetate and hypoxia.
The active pressure (AP) and the oxygen consumption (VO2) of segments of bovine bronchi were measured during a 10 microM carbachol stimulation. VO2 did not increase during the carbachol-induced contraction whereas there was a twofold increase in the lactate production. Addition of the glycolytic blocker, iodoacetate (83 microM), decreased the AP to 68.9 +/- 6.4% of control value (n = 10, P < 0.05) whereas VO2 remained constant. The lactate concentration in the physiological solution decreased significantly (P < 0.05). When the solution was supplemented with pyruvate (10 mM), the effect of iodoacetate was antagonized. Under hypoxic condition, i.e. when the solution was bubbled with 5% CO2 in N2, VO2 decreased sharply to 7.7 +/- 3.1% of control (n = 8, P < 0.05) whereas AP did not change. The combined effect of iodoacetate and hypoxia led to a fall in both AP (12.4 +/- 3.0% of control, n = 7, P < 0.05) and VO2 (21.2 +/- 5.1%, P < 0.05). These results suggest that the energy required by bronchial smooth muscle to generate contraction could be supplied by either the aerobic or the anaerobic pathway.
Zhao
W
W
Laboratoire de Physiologie, Faculté de Médecine Victor Pachon, Université de Bordeaux II, France.
Guénard
H
H
D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D002417:Cattle; D004734:Energy Metabolism / Q000187:drug effects*; D000860:Hypoxia / Q000378:metabolism*; D066298:In Vitro Techniques; D007461:Iodoacetates / Q000494:pharmacology*; D019807:Iodoacetic Acid; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption; D011312:Pressure
D007461:Iodoacetates; D007773:Lactates; D019344:Lactic Acid; D002217:Carbachol; D019807:Iodoacetic Acid