We investigated the mechanisms by which hypoxia and alkalinization inhibit the endothelium-dependent relaxation to Substance P (SP) in porcine coronary artery. In a KCl contracture, the major component of the SP response is endothelium-derived nitric oxide (EDNO), whereas with receptor-mediated 9,11-dideoxy-llalpha, 9alpha-epoxymethanoprostaglandin F(2alpha) (U46619) stimulation, the SP respons...

Mechanisms involved in basolateral HCO transport were examined in the in vitro microperfused rat medullary thick ascending limb of Henle (MTALH) by microfluorometric monitoring of cell pH. Removing peritubular Cl(-) induced a cellular alkalinization that was inhibited in the presence of peritubular 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and blunted in the absence of external CO...

The intracellular pH (pHi) of Dictyostelium discoideum amebae has been determined using the pH-dependent fluorescence of intracellularly trapped fluorescein (Thomas, J. A., R. N. Buschbaum, A. Zimiak, and E. Racker, Biochemistry, 18:2210-2218). The pHi of cells measured 45-60 min after initiation of differentiation was between 6.2 and 6.3. At approximately 2 h into differentiation cells underwe...

The extracellular pH (pHe) of many solid tumors is acidic as a result of glycolytic metabolism and poor perfusion. Acidity promotes invasion and enhances metastatic potential. Tumor acidity can be buffered by systemic administration of an alkaline agent such as sodium bicarbonate. Tumor-bearing mice maintained on sodium bicarbonate drinking water exhibit fewer metastases and survive longer than...

Suspension-cultured tomato (Lycopersicon esculentum) cells react to stimulation by chitin fragments with a rapid, transient alkalinization of the growth medium, but behave refractory to a second treatment with the same stimulus (G. Felix, M. Regenass, T. Boller [1993] Plant J 4: 307-316). We analyzed this phenomenon and found that chitin fragments caused desensitization in a time- and concentra...

A quantitative and robust bioassay to assess plant defense response is important for studies of disease resistance and also for the early identification of disease during pre- or non-symptomatic phases. An increase in extracellular pH is known to be an early defense response in plants. In this study, we demonstrate extracellular alkalinization as a defense response in potatoes. Using potato sus...

35 36 37 Extracellular acidification induced by retinal horizontal cells has been 38 hypothesized to underlie lateral feedback inhibition onto vertebrate 39 photoreceptors. To test this hypothesis, the H-sensitive fluorophore HAF (540 hexadecanoylaminofluorescein) was used to measure changes in H from 41 horizontal cells isolated from the retina of the catfish. HAF staining conditions 42 were m...

Salt pollution and human-accelerated weathering are shifting the chemical composition of major ions in fresh water and increasing salinization and alkalinization across North America. We propose a concept, the freshwater salinization syndrome, which links salinization and alkalinization processes. This syndrome manifests as concurrent trends in specific conductance, pH, alkalinity, and base cat...

We designed the present study to clarify whether the intracellular pH change by ammonium chloride influences endothelium-dependent relaxation in thoracic aorta of 9-week-old Sprague-Dawley rats. Intracellular alkalinization with 3 mmol/L ammonium chloride, which did not affect resting vascular tone, attenuated acetylcholine-induced relaxation but not nitroglycerin vasodilation. Acetylcholine re...