H-SENSITIVITY OF CULTURED NEURONS FROM THE DORSOMEDIAL AND VENTROLATERAL MEDULLA OF NEONATE RATS()

The H+-sensitivity of neonate rat cultured neurons derived from the do rsomedial medulla (DMM) containing the nucleus tractus solitarii and t he ventrolateral medulla (VLM) was determined by H+-sensitive fluoresc ent probe BCECF-AM and immunohistochemical methods. Against an extrace llular pH as low as 7.2-7.3, H+-sensitivity was verified in 2.6% of th e DMM neurons (46/1800) and 2.1% of the VLM neurons (38/1800). This H-sensitive neurons of the DMM were immunoreactive to glutamate (52.4%) and glutamic acid decarboxylase (GAD) (28.6%), while those of the VLM were immunoreactive to glutamate (66.7%) and GAD (33.3%). There was n o immunoreactivity to tyrosine hydroxylase, phenylethanolamine-N-methy ltransferase or choline acetyltransferase in the H+-sensitive neurons are present in the DMM and VLM besides the ventral medullary surface, the site of the central chemoreceptors. (C) 1998 Elsevier Science Irel and Ltd. All rights reserved.