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Figure 6 | BMC Physiology

Figure 6

From: Sinoatrial tissue of crucian carp heart has only negative contractile responses to autonomic agonists

Figure 6

Depression of atrial contraction force by blockade of I Ca . To estimate the contribution of ICa inhibition to CCh's response in the intact sinoatrial tissue, ICa was specifically blocked with 0.84·10-6 M nifedipine, a concentration that causes about 30% inhibition of ICa i.e. similar ICa inhibition as CCh causes at the concentration of 10-7 M. Representative recordings of contraction from warm-acclimated and cold-acclimated fish hearts (left) and mean responses of force (Fmax), duration of contraction (DC) and heart rate (HR) to nifedipine. Nifedipine causes 34% and 41% inhibition of contractile force for warm-acclimated and cold-acclimated fish, respectively, and slight reduction in duration of contraction. Furthermore, nifedipine slightly depressed heart rate (HR) in cold-acclimated fish but not in warm-acclimated fish. The results are means ± SEM of 6 preparations for both acclimation groups.

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