title: Phenotype-specific expression of T-type calcium channels in neurons of the major pelvic ganglion of the adult male rat.
abstract: 1. Neurons from the major pelvic ganglia (MPG) of adult male rats were enzymatically dissociated and the neurochemical phenotype and Ca2+ current properties examined. 2. Neurons were divided into two subpopulations based on the presence or absence of low threshold T-type Ca2+ channels. The subpopulation of neurons expressing T-type Ca2+ channels was characterized by a mean diameter of 34 microns, a mean membrane capacitance (Cm) of 72 pF, tyrosine hydroxylase immunoreactivity (TH-IR), a lack of NADPH diaphorase (NADPHd) reactivity and a high degree of alpha 2-adrenoceptor-mediated Ca2+ current inhibition (60%). 3. The subpopulation of neurons without overt T-type Ca2+ channels had a mean diameter of 23 microns, a mean Cm of 30 pF, a lack of TH-IR and a moderate degree of alpha 2-adrenoceptor-mediated Ca2+ current inhibition (27%). About 50% of this subpopulation stained positively for NADPHd. 4. The contribution of high threshold N-type Ca2+ channels (60-70%), as determined from omega-conotoxin GVIA inhibition, and L-type Ca2+ channels (< 10%), as determined from nifedipine inhibition, to the whole-cell Ca2+ current was similar for both subpopulations of neurons. 5. These data indicate that the MPG contain at least two subpopulations of postganglionic neurons, i.e. adrenergic and non-adrenergic, with distinct electrophysiological and neurochemical properties. Furthermore, we propose that the presence or absence of T-type Ca2+ channels provides an electrophysiological means of identifying adrenergic and non-adrenergic phenotype, respectively, in neurons of the male rat MPG.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta 30912-2300, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.forename: E L
authors.initials: EL
authors.lastname: Zboran
authors.forename: S R
authors.initials: SR
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000235:genetics*; D002452:Cell Count; D015870:Gene Expression / Q000235:genetics; D007001:Hypogastric Plexus / Q000502:physiology*; D008297:Male; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009474:Neurons / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010641:Phenotype; D051381:Rats; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D014446:Tyrosine 3-Monooxygenase; D009252:NADPH Dehydrogenase; D009543:Nifedipine