Ivabradine augments high-frequency dynamic gain of the heart rate response to low- and moderate-intensity vagal nerve stimulation under beta-blockade

Am J Physiol Heart Circ Physiol. 2021 Apr 23. doi: 10.1152/ajpheart.00057.2021. Online ahead of print.ABSTRACTOur previous study indicated that intravenously administered ivabradine (IVA) augmented the dynamic heart rate (HR) response to moderate-intensity vagal nerve stimulation (VNS). Considering an accentuated antagonism, the results were somewhat paradoxical; i.e., the accentuated antagonism indicates that an activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels via the accumulation of intracellular cyclic adenosine monophosphate (cAMP) augments the HR response to VNS, whereas the inhibition of HCN channels by IVA also augmented the HR response to VNS. To remove the possible influence from the accentuated antagonism, we examined the effects of IVA on the dynamic vagal control of HR under beta-blockade. In anesthetized rats (n = 7), the right vagal nerve was stimulated for 10 min according to binary white noise signals between 0 and 10 Hz (V0-10), between 0 and 20 Hz (V0-20), and between 0 and 40 Hz (V0-40). The transfer function from VNS to HR was estimated. Under beta-blockade (propranolol, 2 mg/kg, i.v.), IVA (2 mg/kg, i.v.) did not augment the asymptotic low-frequency gain but increased the asymptotic high-frequency gain in V0-10 (0.53 ± 0.10 vs. 1.74 ± 0.40 beats·min-1·Hz-1, P
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Source Type: research

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Source: Brazilian Journal of Anesthesiology - Category: Anesthesiology Source Type: research
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Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Tags: Am J Physiol Heart Circ Physiol Source Type: research
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