Regulation of intracellular pH in proximal tubules of avian long-looped mammalian-type nephrons

Abstract

In nonperfused proximal tubules isolated from chicken long-looped mammalian-type nephrons, intracellular pH (pHi), measured with the pH-sensitive fluorescent dye 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, was ∼7.3 under control conditions (HEPES-buffered medium with pH 7.4 at 37°C) and was reduced to ∼7.0 in response to NH4Cl pulse. The rate of recovery of pHi from this level to the resting level was 1) significantly reduced by the removal of Na+ from the bath, 2) significantly increased by the removal of Cl− from the bath, 3) unchanged by the removal of both Na+ and Cl− from the bath, 4) significantly reduced by the addition of either ethylisopropylamiloride or DIDS to the bath, 5) significantly increased by a high bath K+ concentration, and 6) unchanged by the addition of Ba2+ to the bath. These data suggest that both Na+-coupled and Cl−-coupled basolateral acid-base fluxes are involved in determining the rate of recovery of pHi after acidification. The most likely ones to be important in regulating pHi are a Na+/H+exchanger and a Na+-coupled Cl−/[Formula: see text]exchanger. In birds, long-looped mammalian-type nephrons resemble short-looped transitional nephrons but differ markedly from superficial loopless reptilian-type nephrons.

Uptake of histamine by mouse peritoneal macrophages and a macrophage cell line, RAW264.7

“…A mouse macrophage cell line, RAW264.7, was grown in RPMI-1640 medium supplemented with 10% heat-inactivated fetal calf serum, 100 U/ml penicillin, and 0.1 mg/ml streptomycin, in 5% CO 2 33 Ci/ml) in the presence of cold histamine for the indicated periods at 37°C. The cells were rinsed twice in ice-cold PBS and lysed with PBS containing 1% Triton X-100.…”

“…Chloroquine dose dependently suppressed histamine uptake. Histamine uptake was also suppressed (70.0 Ϯ 4.51% of control) after intracellular acidification by preloading the cells for 15 min with 30 mM NH 4 Cl, according to the procedure reported previously (2).…”

A vacuolar-type H+-ATPase and a Na+/H+exchanger contribute to intracellular pH regulation in cockroach salivary ducts

“…Its activity rises with decreasing pH i , and the existence of a H + binding site for the allosteric activation of NHE activity by internal H + has been postulated (Wakabayashi et al, 1997). Thus, in many NHEexpressing cell types, this transporter is not involved in the regulation of resting pH i (Tønnessen et al, 1990;Brokl et al, 1998;Tsuchiya et al, 2001) but becomes active after an acute acid load. As shown in rat sublingual mucous acini, for example, the rate of pH i recovery after an NH 4 Cl-induced acid load increases linearly with decreasing pH i as a result of differences in NHE activity (Zhang et al, 1992).…”

Intracellular pH in isolated rat renal papillary thin limbs of Henle's loop

“…We used the pH-sensitive fluorescent dye 2′,7′-bis (2-carboxyethyl)-5,6-carboxyfluorescein (BCECF) to measure pH i in a manner similar to that described by others and also used by us [8,22,23,27,28]. For these measurements, we used a dual-wavelength spectrofluorimeter built around an Olympus IMT-2 inverted epifluorescence microscope as described previously [8].…”

“…For these measurements, we used a dual-wavelength spectrofluorimeter built around an Olympus IMT-2 inverted epifluorescence microscope as described previously [8]. Briefly, a 100-W mercury arc lamp was used as an excitation source and specific excitation wavelengths for measurement of pH using BCECF were selected by a filter wheel.…”