Interstitial PCO2 and pH, and their role as chemostimulants in the isolated respiratory network of neonatal rats.

Abstract

1. C02-H+-sensitive microelectrodes were used for simultaneous measurements of the partial pressure of CO2 (PC02) and extracellular pH (pH.) Central chemoreceptors play a crucial role in the control of regarding the primary mechanism of central chemobreathing. Respiration is primarily stimulated by protons, sensitivity, it is also questionable whether the chemoreceptive but CO2 is assumed to exert a direct response in addition to structures are restricted to the classical areas at the ventral its indirect effect, caused by elevation of extracellular H+ surface of the medulla, originally described by the groups of activity during hypercapnia (see Loeschcke, 1982; cf. Mitchell and Loeschcke (Loeschcke,

Carbonic Anhydrase Isoform VII Acts as a Molecular Switch in the Development of Synchronous Gamma-Frequency Firing of Hippocampal CA1 Pyramidal Cells

“…These experiments were performed in the continuous presence of BA because, in slices, the initial ⌬pH i /⌬t is rate-limited not only by the intracellular CO 2 /HCO 3 Ϫ hydration/dehydration reaction but also by the diffusion of carbonic acid buffer species within the tissue (Voipio and Ballanyi, 1997). In agreement with the data from isolated neurons, EZA had no discernible effect on the pH i response of hippocampal CA1 pyramidal neurons in the P0 -P8 slices (Fig.…”

Protective role of neuronal KATP channels in brain hypoxia

“…A similar persistence of respiratory activity at greatly reduced frequency for anoxia periods of up to 1·h is observed in brainstem-spinal cord preparations from newborn rats ( Fig.·7A; Ballanyi et al, 1994Ballanyi et al, , 1999Ballanyi, 2004). A series of reports on the latter preparation Brockhaus et al, 1993;Voipio and Ballanyi, 1997;Ballanyi, 2004) has led to the view that the high tolerance of the respiratory network in newborn mammals to oxygen depletion includes two cooperative processes. On the one hand, anoxia appears to effectively stimulate anaerobic glycolysis ('Pasteur effect'; Lutz and Nilsson, 1994;Hochachka and Lutz, 2001).…”

Transport Activity of the High-affinity Monocarboxylate Transporter MCT2 Is Enhanced by Extracellular Carbonic Anhydrase IV but Not by Intracellular Carbonic Anhydrase II

“…Similarly, as in the cytoplasm, diffusion of ions in the extracellular space is restricted. For the brain, where MCT2 and CAIV are coexpressed in some types of neurons (16), it has been shown, that extracellular diffusion of ions is hindered by tortuosity of the extracellular space, proteoglycans at the outer membrane surface, charges at the extracellular matrix, but also by extracellular buffers (49,50). Therefore it appears likely that an effective cotransport of lactate and H ϩ across the cell membrane does require proton handling on both sides of the plasma membrane.…”