Parathyroid hormone control of free cytosolic Ca2+ in the kidney.
We have established a perifusion system to monitor free cytosolic calcium concentrations ([Ca2+]i) in mouse kidney slices, which presumably reflects in vivo status more accurately than renal cells in culture, by means of the fluorescent calcium indicators quin-2 and fura-2. An increase in the extracellular calcium concentrations from 0 (no added Ca2+) to 3.0 mM resulted in an increase in [Ca2+]i from 52 to 239 nM. Replacement of 118 mM of extracellular Na+ with choline, or the addition of ouabain, an inhibitor of Na+,K+-ATPase, at 10(-6) M in the perfusate caused an increase in [Ca2+]i from 161 +/- 13 to 873 +/- 78 nM (n = 10) and 161 +/- 13 to 395 +/- 68 nM (n = 4), respectively, suggesting the possible existence of a Na+,Ca2+ exchange mechanism in the kidney slice. We further examined the effects of PTH on [Ca2+]i mobilization in the kidney. Both human PTH-(1-34) and hPTH-(1-84) increased [Ca2+]i within 60 s at physiologic concentrations of 10(-11)-10(-9) M in a dose-dependent manner. On the other hand, an increase in intracellular cAMP in the slice was also detected above 3 X 10(-9) M hPTH-(1-34) [base 2.1 +/- 0.4 pmol/mg, 3.2 +/- 0.6 pmol/mg (p less than 0.05 versus control values) 5 minutes after the application of 3 X 10(-9) M hPTH-(1-34) and 17.3 +/- 4.3 pmol/mg (p less than 0.05 versus control values) 3 X 10(-8) M hPTH-(1-34), mean +/- SEM, n = 7, p less than 0.05 versus control values].(ABSTRACT TRUNCATED AT 250 WORDS)
Fujii
Y
Y
Department of Medicine, Kobe University School of Medicine, Japan.
Fukase
M
M
Tsutsumi
M
M
Miyauchi
A
A
Tsunenari
T
T
Fujita
T
T
D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000032:analysis; D003600:Cytosol / Q000378:metabolism*; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D010042:Ouabain / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology
D000634:Aminoquinolines; D005456:Fluorescent Dyes; D010281:Parathyroid Hormone; D010042:Ouabain; C035738:Quin2-acetoxymethyl ester; D012964:Sodium; D000242:Cyclic AMP; D002118:Calcium