Effects of neuromuscular‐blocking drugs in rats in vivo: Direct measurements in the diaphragm and tibialis anterior muscle

Abstract

Neuromuscular-blocking effects on the diaphragm can be recorded in vivo. According to direct contractile force measurement, the diaphragm is more resistant to non-depolarizing neuromuscular-blocking drugs than the tibialis anterior muscle.

Different recovery of the train-of-four ratio from rocuronium-induced neuromuscular blockade in the diaphragm and the tibialis anterior muscle in rat

“…In our previous study in rats [6], where we stimulated only the right phrenic nerve, the fourth-twitch response to TOF stimuli was small, and the TOF ratio could not be determined accurately. In the current study, we stimulated both phrenic nerves via a bilateral thoracotomy, resulting in larger twitch tensions and more accurate TOF ratios.…”

“…When we previously studied the ED50 of rocuronium for the diaphragm and the tibialis anterior muscle by cumulative-infusion drug administration in an animal model [6], the ED ratio at ED50 was 2.30. Thus, the ED ratios at ED50 according to the two methods were similar, while Cantineau et al [4] reported that the ED ratio, at ED50, between the diaphragm and the adductor pollicis muscle in human subjects was 1.86.…”

“…After a steady state had been maintained for 30 min or more, rocuronium was injected intravenously, at doses ranging from 0.7 to 1.2 mg·kg −1 , in the phrenic nervediaphragm preparation, and at doses ranging from 0.40 to 0.51 mg·kg −1 in the sciatic nerve-tibialis anterior muscle preparation. These doses were chosen according to the effective doses for 50% blockade (ED50) determined in our previous experiments [6] and in a preliminary study. We applied linear regression to a dose-response curve relating the logarithm of the dose (on the abscissa) to the probit transformation of the percent maximal block (on the ordinate).…”

Resistance to d-Tubocurarine of the Rat Diaphragm as Compared to a Limb Muscle

“…The different potency of D-tubocurarine presently observed in vitro in the rat between the diaphragm and the EDL corroborates our previous findings in the mice. 11 In comparison, a 2.5-to 3-fold potency ratio of steroidal NMBA was observed in vivo in the rat, 14 whereas a 7-fold D-tubocurarine effective concentration ratio was observed in the current study. This difference can probably be explained by differences between the in vivo and in vitro conditions.…”

Resistance to rocuronium of rat diaphragm as compared with limb muscles

“…However, the values of IC 50 calculated in the present study were not completely accordant with previous findings. Itoh et al [35] estimated neuromuscular effects of rocuronium by direct measurement of twitch tension with a force transducer using a cumulative infusion dosing method where a 2.5-to 3-fold potency ratio of as DIA to the tibialis anterior muscle was observed in vivo in rat. While in Nguyen-Huu et al [3] study, they compared the IC 50 in DIA and EDL to d-tubocurarine, and 7-fold effective concentration ratio was observed.…”