RETRACTED: NICARDIPINE ENHANCES DIAPHRAGMATIC FATIGUE (Retracted article. See vol. 59, pg. 1179, 2012)

The effects of nicardipine, a calcium channel blocker, on diaphrogmatic 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 mu g.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.