Simultaneous measurement of intracellular pH, calcium, and tension in rat mesenteric vessels: effects of extracellular pH.
In rat mesenteric vessels changes in external pH (pHo) alter tension. Changes in intracellular pH (pHi) and calcium ([Ca2+]i) have both been suggested to underlie the tension changes. As no simultaneous measurements of pHi and [Ca2+]i had been made, however, the relative importance and temporal relationship between pHi [Ca2+]i and tension were unknown. In order therefore to gain a clearer understanding of the mechanisms involved, we have made simultaneous measurements of these parameters using carboxy-SNARF and INDO-1. Raising pHo caused rises in pHi, Ca2+ and tension. The increases in pHi preceded increases in [Ca2+]i, which preceded the increases in tension. Similar but opposite effects were observed when pHo was decreased. We conclude that the change in [Ca2+]i upon alteration of pHo is subsequent to that of pHi.
Austin
C
C
Department of Physiology, University of Liverpool, United Kingdom.
Dilly
K
K
Eisner
D
D
Wray
S
S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007211:Indoles; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013050:Spectrometry, Fluorescence; D013152:Splanchnic Circulation; D013314:Stress, Mechanical
D005456:Fluorescent Dyes; D007211:Indoles; C048960:indo-1; D002118:Calcium