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. Author manuscript; available in PMC: 2020 Aug 1.
Published in final edited form as: J Physiol. 2019 Jul 11;597(15):3867–3883. doi: 10.1113/JP278016

Figure 3.

Figure 3.

Impact of β-adrenergic stimulation and heart rate (HR) on action potential duration (APD) and Ca2+ transient duration (CaTD) in the mouse heart. (A) Example optical APs and normalized CaTs recorded 20 sec after acute tyramine (20 μM) infusion. (B-C) HR, APD, and CaTD over 60 sec following acute tyramine (20 μM) bolus infusion (B) or acute noradrenaline (50 nM) bolus infusion (C) (*p<0.05 vs. time 0, n=4). (D) HR, APD, and CaTD during 60 sec of sympathetic nerve stimulation (SNS) following pre-treatment with propranolol (10 μM, n=3). (E) APD in response to a step-wise increase in pacing frequency (red line), without (black line) and with (blue line) concomitant SNS (*p<0.05 vs. time 0, n=3). (F) APD over 60 sec of constant pacing at a cycle length (CL) of 100ms without (black line) and with (blue line) 60 sec of SNS (*p<0.05 vs. time 0, n=5).