Quantitative Aspects of the Sympathetic Neuro‐hormonal Control of the Heart Rate

Summary. In cats stimulation of the accelerans nerves exerts a much stronger effect on the heart rate than the hormones released at a similar activation of the adrenal medullas. This is in accordance with the characteristics of the sympatho‐adrenal control of other autonomic effectors. The heart response is sometimes seen to vanish quite rapidly on interruption of a low‐frequency accelerans nerve stimulation. It is therefore discussed whether the prompt reflex decreases of stroke volume, known to occur on baroceptor stimulation in man, really necessitate the assumption of a direct vagal control of the heart ventricles. It is after all not impossible that this is the consequence of an inhibition of a tonic sympathetic influence on the heart and adjacent capacity vessels, factors which both must result in some decrease of stroke volume.