Carotid chemoreceptor reflex in rats during experimental tetanus toxicity.

The effects of stimulation of carotid body chemoreceptors on blood pressure, heart rate and ventilation were compared in normal rats and rats with local or generalised tetanus toxicity induced by injection of the toxin. Carotid chemoreceptor stimulation in an increase in blood pressure and a decrease in heart rate in both control and tetanus rats. However, while chemoreceptor stimulation resulted in increases in ventilation of 115% and 123% in normal rats and rats with local tetanus respectively, the increase in rats with generalised tetanus was only 29%. The experiments indicate that normal rats and rats with tetanus toxicity exhibit identical pressor and heart rate responses to stimulation of carotid chemoreceptors whereas the ventilatory response is attenuated in the tetanus rats.