Responses of Cat Petrosal Ganglion Neurons are Modified by the Presence of Carotid Body Cells in Tissue Cultures

Abstract

The carotid body glomus (type I, receptor) cells are the sensory elements of the arterial chemoreceptor system. They are innervated by petrosal ganglion neurons that convey chemosensory information to the central nervous system. It is accepted that the transduction of the chemosensory stimuli in the glomus cells produces the exocytotic release of several transmitters and/or modulators that, acting on the neuronal terminal, drive the sensory activity (for review see González et al, 1994). However, there is limited information on the membrane potential changes induced in the petrosal ganglion neurons by effect of carotid chemosensory stimulation. Intracellular recordings from the nerve terminals within the carotid body showed the existence of slow, graded potentials that could generate spikes when they reach threshold (Hayashida et al, 1980), resembling synaptic or receptor potentials. Recently, acid-induced depolarizing responses, generating trains of action potentials when threshold was reached, were recorded from vagal sensory neurons co-cultured with carotid body cells (Alcayaga & Eyzaguirre, 1990). There is though, a degree of specificity in the formation of synapses between neurons and their target tissues, so we investigated the properties and responses of petrosal ganglion neurons of adult cats, both alone and in presence of carotid body tissue.