Effects of ouabain on tetanic force development in rat soleus exposed to direct stimulation at 60 Hz in K.R. buffer or in air. Experimental conditions as described in the legend to Fig. 2, but muscles were first tested using 2-s trains of 60 Hz stimulation in buffer without (filled symbols) or with (open symbols) ouabain (10−5 M). After 10 min of incubation in buffer without or with ouabain, the buffer was aspirated and all muscles exposed to continuous stimulation at 60 Hz for 180 s, followed by 2-s trains of 60-Hz stimulation at the indicated intervals. Finally all muscles were washed three times in K.R. without ouabain, left in buffer, and tetanic force tested at the indicated intervals. Each point represents the mean of observations on three to four muscles with bars denoting SEM.
