Anesthesiology
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Using an extracellular microelectrode recording technique, the effects of intravenously administered morphine sulfate upon the single-unit activities of cells in Rexed lamina VII of the lumbar spinal cord were studied in cats following decerebration and spinal cord transection at L1. These neurons responded principally to high-threshold mechanical and thermal stimuli applied to a receptive field in the ipsilateral hind limbs. ⋯ The firing rates at maximum suppression, observed 5-10 min after administration of morphine, were 63.9 +/- 9.2 (mean +/- 1 SE), 43.0 +/- 5.4, and 26.5 +/- 6.0 per cent of the control values, respectively. Since these cells have been shown by others to be associated with the spinothalamic and spinoreticular pathways, the results suggest that the analgesic state may result from the action of morphine on the cells of origin of these major ascending pathways in the spinal cord.
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Clinical Trial
Relationship of the serum concentration of pancuronium to its neuromuscular activity in man.
The relationship between the time course of the decay of serum concentrations of pancuronium and its neuromuscular blocking effect has been investigated after the intravenous administration of 50, 80 and 100 microgram/kg doses to anesthetized patients. Following administration of these doses, maximal neuromuscular block in the adductor pollicis muscle developed in about 7, 2.5, and 2 minutes and lasted about 20, 40, and 60 minutes, respectively. ⋯ Neuromuscular transmission to the adductor pollicis muscle started to recover at a mean serum pancuronium concentration of 0.21 +/- 0.03 microgram/ml. The data obtained in this study are in agreement with the experimental and clinical findings of similar studies with d-tubocurarine, and indicate that there is a correlation between the serum concentrations of muscle relaxants and the intensity of their neuromuscular activities.