Cardiac mechanisms of acetylcholineInotropy -Chronotropy-Na(I)Dromotropy -NorEplAChHHHTMuscanmcBeta-1ReceptorReceptorGGStimulatesStimulates-Cyelic-AMPInhibition
Cardiac mechanisms of acetylcholine Inotropy - Chronotropy - Dromotropy -
Mechanisms of acetylcholine-increasedK+permeability·K+ outward ↑, JMRPl ↑, phase 4 spontaneousdepolarization ↓, Autorhythmicity ↓· Inhibition of Ca2+ channel, phase O amplitude &velocity ↓， Conductivity ↓·Ca2+ influx ↓,[Ca2+l: ↓, Contractility
• Ca2+ influx ↓, [Ca2+ ] i ↓, Contractility ↓ — increased K+ permeability Mechanisms of acetylcholine • K+ outward ↑, |MRP| ↑, phase 4 spontaneous depolarization ↓, Autorhythmicity ↓ • Inhibition of Ca2+ channel, phase 0 amplitude & velocity ↓, Conductivity ↓
wLLuCardiaceffect ofparasympatheticstimulationParasympatheticstimulationBeforevagal stimulationDuringvagal stimulation10075M(6HWW)50250小+P/dpO01234.512345Time (s)
Cardiac effect of parasympathetic stimulation
Predominance of autonomic nerves120Propranolol110100se)aAtropine90a-receptorblocker807060PropranololAtropine50β-receptorblocker40.2343ControlFirstdrugadministeredSeconddrug administered
Predominance of autonomic nerves α-receptor blocker β-receptor blocker
CardiovascularCenterA collection of functionally similar neurons thathelp to regulate HR, SV, and blood vessel tone(diameter)
A collection of functionally similar neurons that help to regulate HR, SV, and blood vessel tone (diameter). Cardiovascular Center