title: The influence of respiratory-induced acid-base changes on the action of non-depolarizing muscle relaxants in rats.
abstract: The influence of respiratory-induced acid-base changes on the action of non-depolarizing muscle relaxants was investigated using the rat phrenic nerve-hemidiaphragm preparation. Changes in pH were induced by changes in the CO2 concentration aerating Krebs' solution. In the absence of muscle relaxants, an increase in CO2 from 5% to 7.5% decreased (P less than 0.01) indirectly elicited twitch tension by 5.4 +/- 0.7% (mean +/- SEM), while a decrease in CO2 from 5% to 2.5% increased (P less than 0.01) twitch tension by 2.3 +/- 0.7%. With a change in CO2 from 2.5% to 7.5%, partial neuromuscular blockade produced by d-Tc or vecuronium was augmented (P less than 0.01), while that produced by metocurine, pancuronium, or alcuronium was reduced (P less than 0.01). With the change in CO2 from 7.5% to 2.5%, the neuromuscular blockade produced by d-Tc or vecuronium was reduced (P less than 0.01), while that produced by metocurine, pancuronium, or alcuronium was augmented (P less than 0.01). Dose-response study showed that 2.5% CO2 shifted the dose-response curves for d-Tc and vecuronium to the right (P less than 0.01) from those with 5% CO2, whereas 7.5% CO2 shifted them to the left (P less than 0.05). In contrast, neither 2.5% CO2 or 7.5% CO2 significantly shifted the dose-response curves for metocurine or pancuronium from those with 5% CO2. Their dose-response curves with 2.5% CO2 were to the left, instead of to the right, of those with 7.5% CO2 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000142:Acidosis, Respiratory / Q000503:physiopathology*; D000472:Alkalosis, Respiratory / Q000503:physiopathology*; D000818:Animals; D008297:Male; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D010197:Pancuronium / Q000494:pharmacology; D051381:Rats; D009435:Synaptic Transmission / Q000187:drug effects*; D014403:Tubocurarine / Q000031:analogs & derivatives / Q000494:pharmacology; D014673:Vecuronium Bromide / Q000494:pharmacology
chemical_list: D009466:Neuromuscular Blocking Agents; D014673:Vecuronium Bromide; D010197:Pancuronium; C032943:metocurine; D014403:Tubocurarine