Key result
Yohimbine increased the maximum step response of heart rate from 7.2 to 12.2 beats/min (P<0.05), whereas higher dose clonidine decreased it from 6.3 to 2.8 beats/min (P<0.05).
Absolute Event Rate: 12.2% vs 7.2%
p-value: p=<0.05
Presynaptic alpha2-adrenergic autoinhibition limits the maximum heart rate response without slowing it, whereas pharmacologic augmentation attenuates the maximum response and slows the effector response.
No takes yet. Share an insight, caveat, or question.
Alpha2-adrenergic effects on heart rate dynamics should not change practice; leaves open mechanistic targets for human autonomic research.
Miyamoto et al. (2008) studied Anesthetized rabbits (n=11). Yohimbine and Clonidine vs. Baseline (without blockade/augmentation) was evaluated on Maximum step response of heart rate (p=<0.05). Yohimbine increased the maximum step response of heart rate from 7.2 to 12.2 beats/min (P<0.05), whereas higher dose clonidine decreased it from 6.3 to 2.8 beats/min (P<0.05).
Synapse has enriched 3 closely related papers on similar clinical questions. Consider them for comparative context: