Reflex changes in heart rate after mechanical and thermal stimulation of the skin at various segmental levels in cats

Heart rate can be changed by cutaneous stimulation. In anesthetized cats with the central nervous system intact, a reflex increase in heart rate was elicited after natural stimuli such as pinching (noxious mechanical stimulation), rubbing (non-noxious mechanical stimulation), warming and cooling (thermal stimuli) were applied to the skin of the neck, chest, abdomen or perineum. It was shown that this cutaneo-cardiac acceleration reflex was produced mainly by a reflex increase in the discharges of the cardiac sympathetic efferent nerves and partially by a reflex decrease in the discharges of the cardiac vagal efferent nerves. On the other hand, in spinal cats, only stimulation of the chest and abdominal skin produced a reflex increase in heart rate. A possible explanation of this difference between central nervous system intact and spinal cats is that a spinal, segmentally organized component of the cutaneo-cardiac acceleration reflex is dominated by a supraspinal, diffusely distributed component in central nervous system intact cats.