Oxygen and acid chemoreception in the carotid body chemoreceptors

Effects of hypercapnia on membrane potential and intracellular calcium in rat carotid body type I cells.

“…11) is consistent with the presence of Na+-Ca2+ exchange in this tissue, since under conditions of elevated [Ca2+]i the exchanger would be expected to contribute to Ca2+ efflux. Our results, however, do not provide incontrovertible proof of Na+-Ca2+ exchange activity since, under sodium-free conditions, the type I cell is known to acidify (Buckler, Vaughan-Jones, Peers & Nye, 1991b) (Rocher et al 1991;Gonzalez et al 1992). Ca2+ influx may also promote Ca2+ release from internal stores, but as the size of the caffeine-releasable Ca2+ pool in these cells seems to be small (Fig.…”

“…Are the mechanisms of acidic chemotransduction in the rat different from those in the rabbit Gonzalez and colleagues (Rocher et al 1991;Gonzalez et al 1992) have presented an hypothesis for acid chemotransduction in which intracellular acidosis activates Na+-dependent acid extrusion mechanisms (e.g. Na+-H+ exchange, and a Na+-HCO3 -dependent transporter; see Buckler et al 1991 …”

“…One possible mechanism is that an intracellular acidosis causes cell membrane depolarization, by the inhibition of potassium channels, which leads to voltage-gated Ca2" entry (Peers, 1990;Peers & Green, 1991;Stea, Alexander & Nurse, 1991). An alternative mechanism is that the fall in pHi activates Na+-H+ exchange leading to a rise in intracellular Na+ and subsequent Ca2+ entry via Na+-Ca2+ exchange (Rocher et al 1991;Gonzalez, Almarez, Obeso & Rigual, 1992). In order to determine whether either of the above proposals accounts for acid chemoreception, we have investigated the mechanism by which a hypercapnic acidosis elevates [Ca2+]j in enzymatically isolated, neonatal rat, carotid body type I cells.…”

Electrical activity and behavior in the pharynx of caenorhabditis elegans

“…This neuronal process may have a mechanosensory function that is able to sense the contraction. Recently, physiological demonstrations of bifunctional neu'rons have been made in annelids (Wenning et al, 1993), arthropods (Pasztor and Bush, 1989), and vertebrates (for review see Gonzalez et al, 1992). In each of these cases, the neuron is a neurosecretory cell with a sensory function.…”

Inhibition of [3H]catecholamine release and Ca2+ currents by prostaglandin E2 in rabbit carotid body chemoreceptor cells.

“…476.2 Compiling the data from this and the preceding article (Gomez-Nifio et al 1994), a new concept in CB chemoreception emerges, namely that PGE2 is a potent modulator of the 02 chemoreception process. To appreciate this statement fully, it should be recalled that the release of [3H]DA from chemoreceptor cells is a valid index of the chemoreception process (Fidone, Gonzalez, Obeso, GomezNifio & Dinger, 1990;Gonzalez et al 1992). Thus, although the role played by DA at the synapse between chemoreceptor cell and sensory nerve ending is in dispute (see Fidone et al 1990), it has been shown that, in all experimental conditions tested, the release of [3H]DA parallels the simultaneously recorded action potential frequency in the CSN (see Fidone & Gonzalez, 1986;Fidone et al 1990).…”