Free cytosolic Ca2+ measured with Ca(2+)-selective electrodes and fura 2 in rat mesenteric resistance arteries.
Free cytosolic Ca2+ was measured with sub-micrometer-tip, double-barrelled, Ca(2+)-selective electrodes and fura 2 in rat mesenteric resistance arteries. The purpose was to establish intracellular free Ca2+ concentration ([Ca2+]i) values in resting and stimulated vessels. Isolated vessels were mounted for isometric force measurements. Measured with electrodes, mean [Ca2+]i was 115 and 708 nM under resting and norepinephrine-activated conditions, respectively. Fura 2 was calibrated intracellularly including determination of the intracellular dissociation constant (Kd) of the fura 2:Ca2+ complex. The intracellular Kd was 342 nM. With this value of Kd, fura 2 measurements of mean [Ca2+]i were 129 and 537 nM under resting and norepinephrine-activated conditions, respectively. The values measured with the two techniques were thus in good accordance.
Jensen
P E
PE
Department of Pharmacology, University of Aarhus, Denmark.
Mulvany
M J
MJ
Aalkjaer
C
C
Nilsson
H
H
Yamaguchi
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004566:Electrodes; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D016257:Fura-2; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012146:Rest; D014655:Vascular Resistance
D002118:Calcium; D016257:Fura-2; D009638:Norepinephrine