Characterization of cardiorespiratory responses to electrical stimulation of the globus pallidus in cat

The aim of the present study was to describe the characteristics of the electrically elicited cardiorespiratory responses from the globus pallidus (GP) in cat. GP stimulation caused an increase in the arterial blood pressure (BP), heart rate (HR), and respiratory rate (RR) in freely moving cats. Threshold, medium, and high intensity for stimulation at 100 Hz were determined by the somatomotor effects of stimulation. The higher stimulus intensity the higher increase in cardiorespiratory functions was obtained. The electrical stimulation within different segments of the GP caused changed effects. A continuous rise in BP, HR, and RR was induced by stimulating in the external segment (GPe). On the contrary, the stimulation in the internal segment (GPi) produced complex sequence of changes. At the beginning of the 10-s long stimulation the increase in diastolic pressure was more steep than that of the systolic pressure, so the pulse pressure decreased. However, 2-3 a after the onset of stimulation the diastolic pressure reduced; therefore, the pulse pressure increased. Simultaneously, the HR decreased below the prestimulation level. Occasionally, similar slowing in RR appeared as well. The blockade of the alpha(1)-receptors by phentolamine, or neurotoxic lesion within the GP by kainic acid, reduced significantly the BP effects of GP stimulation of identical parameters. It is concluded that GP plays an intricate role in the adjustment of cardiorespiratory functions to the somatomotor activities. (C) 1999 Elsevier Science Inc.