Nicardipine enhances diaphragmatic fatigue.
The effects of nicardipine, a calcium channel blocker, on diaphragmatic fatigue were studied in 20 anaesthetized, mechanically ventilated dogs divided into two groups: control group (Group C, n = 10) and nicardipine group (Group N, n = 10). Diaphragmatic fatigue was induced by intermittent supramaximal electric stimulation to bilateral phrenic nerves at a frequency of 20 Hz for 30 min. In Group N, 5 micrograms.kg-1.min-1 nicardipine iv was infused continuously during this fatigue-producing period. Transdiaphragmatic pressure (Pdi) produced by electrical stimulation (10-100 Hz) of the phrenic nerves was used as an index of diaphragmatic contractility. After a fatigue-producing period, the Pdi in both groups decreased at low frequency (10-30 Hz) stimulation compared with pre-fatigue values (P < 0.05), whereas no change in Pdi was observed at high-frequency (50-100 Hz) stimulation. The decrease of Pdi at low-frequency stimulation was larger in Group N (P < 0.05). The integrated diaphragmatic electric activity (Edi) in both groups did not change at any frequency of stimulation throughout the experiment. We conclude that nicardipine enhances diaphragmatic fatigue.
Fujii
Y
Y
Department of Anaesthesiology, Toride Kyodo General Hospital, Ibaraki, Japan.
Toyooka
H
H
Amaha
K
K
D000818:Animals; D016280:Atrial Function, Right / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D003964:Diaphragm / Q000187:drug effects*; D004285:Dogs; D004576:Electromyography / Q000187:drug effects; D005221:Fatigue / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009529:Nicardipine / Q000494:pharmacology*; D011312:Pressure; D011651:Pulmonary Artery / Q000502:physiology; D011669:Pulmonary Wedge Pressure / Q000502:physiology
D009529:Nicardipine