Cardiac acceleration in man elicited by a muscle-heart reflex

Abstract

The shortening of the R-R interval in response to voluntary and electrically induced isometric muscle contractions of short duration was investigated in 15 volunteers. In some of those experiments the effect of vagal blockade was also studied. The results show: 1) a lag time between the start of the contraction and the following decrease in R-R interval duration of 550 milliseconds; 2) a similar R-R interval response due to voluntary and electrically induced contractions of the same force; 3) no shortening of the R-R interval when the skin is stimulated without ensuing muscular contraction; 4) a complete disappearance of the response to isometric contractions during vagal blockade. A difference in lag time between the onset of arm contraction and cardiac acceleration could not be demonstrated. Most of the results give strong evidence to the existence of a muscle-heart reflex in man, involved in the instantaneous cardiac acceleration at the onset of exercise, that has its origin in the muscles and the vagal nerves as its efferent pathway.

α2B-Adrenergic receptor deletion polymorphism and cardiac autonomic nervous system responses to exercise in obese women

“…It evokes a rapid and sustained increase in HR. 34 The early tachycardia response has been attributed to the cardiac vagal withdrawal, as evidenced by blockade of this response by prior atropinization. The late increase in the HR has been demonstrated to be sympathetic in origin, since it was unaffected by atropine, but suppressed by combined atropine-propanolol blockade.…”

Respiratory and cardiac responses to dynamic exercise in man.

“…These afferents (group III and IV) from free nerve endings are believed to be sensitive to pain, pressure, and metabolites (MITCHELL et a!., 1977). A muscle-heart reflex has been demonstrated (HOLLANDER and BoUMAN, 1975) and even a muscle-heart reflex preceded by a rise in ventilation following a single muscle-twitch such as a handgrip or a kick (PAULEV, 1971(PAULEV, , 1973. The first sign of increased ventilation occurs within 200 ms from the cerebrally initiated elec-tromyographic activity, and the first rise in heart rate occurs within 550 ms (PAULEV, 1973).…”

Cardiovascular autonomic nervous response to postural change in 610 healthy Japanese subjects in relation to age

“…The immediate HR increase on standing (∆H im ) is the result of abrupt inhibition of cardiovascular vagal tone and can be attributed to two operations; one is the central command (Freyschuss, 1970;Maciel et al, 1987;Martin et al, 1974) associated with the centrostaltic reflex, and the other is the exercise reflex (Freyschuss, 1970;Borst et al, 1972;Hollander and Bouman, 1975), which operates as soon as voluntary muscle contractions are performed .…”

“…∆H im represents the tonus of the cardiovascular parasympathetic nerve at rest and the efferent cardiovascular vagal inhibition (Borst et al, 1972;Hollander and Bouman, 1975). The primary HR increase (∆H im ) is temporarily available to maintain cardiovascular output.…”