Figure 1.

M-currents are responsible for the vagal dysfunction and failing autonomic control of HR in SHR. By inhibiting Kv, 3,4-DAP will induce Ach release primarily from preganglionic parasympathetic neurons and norepinephrine from sympathetic nerve endings as indicated, and through that induce bradycardia followed by tachycardia.(Berg, 2015) M-currents (Kv7.2-7.3) hamper neuron excitability. In the parasympathetic branch, the M-channels may be located both in the preganglionic and postganglionic neurons, whereas a postganglionic localization seemed likely in the sympathetic branch. Drug names indicate site of main action. Arrows and blunted arrows indicate stimulatory and inhibitory actions, respectively.