Active Ca2+ transport in primary cultures of rabbit kidney CCD: stimulation by 1,25-dihydroxyvitamin D3 and PTH.
Rabbit connecting tubules and cortical collecting ducts, which represent 79 +/- 5% of the calbindin-D28k-containing kidney cells, were isolated by immunodissection from the rabbit kidney superficial cortex and seeded on permeable filters. After 6 days in culture the monolayers developed a potential difference (PD) of -24 +/- 3 mV (lumen negative) and a transepithelial resistance (R) of 284 +/- 19 omega.cm2. Addition of 10(-6) M amiloride to or removal of Na+ from the mucosal side reversed the PD to +6 +/- 4 mV and concomitantly increased R to 660 +/- 122 omega.cm2. The cells developed functional parathyroid hormone (PTH) and arginine vasopressin receptors, but calcitonin receptors were absent. The monolayer actively absorbed Ca2+ against an electrochemical gradient with a rate of 121 +/- 13 nmol.h-1.cm-2. Removal of serosal Na+ inhibited Ca2+ absorption by 63 +/- 8%. Exposure to 10(-7) M 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] for 48 h or 10(-7) M bovine PTH (bPTH)-(1-34) for 1 h, increased transcellular Ca2+ absorption by 53 +/- 13% or 24 +/- 8%, respectively. The effects of 1,25(OH)2D3 and PTH in combination were neither additive nor potentiating. In addition, the cultured cells expressed calbindin-D28k, and, after exposure to 10(-7) M 1,25(OH)2D3 for 48 h, the calbindin-D28k content increased fourfold.
Bindels
R J
RJ
Department of Physiology, University of Nijmegen, The Netherlands.
Hartog
A
A
Timmermans
J
J
Van Os
C H
CH
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal; D001127:Arginine Vasopressin / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D064092:Calbindin 1; D064026:Calbindins; D002116:Calcitonin / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D007124:Immunoenzyme Techniques; D007672:Kidney Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007684:Kidney Tubules / Q000187:drug effects / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D011817:Rabbits; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D019379:Teriparatide
D000911:Antibodies, Monoclonal; C576499:Calb1 protein, mouse; D064092:Calbindin 1; D064026:Calbindins; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D064030:S100 Calcium Binding Protein G; D019379:Teriparatide; D001127:Arginine Vasopressin; D000584:Amiloride; D000324:Adrenocorticotropic Hormone; D002116:Calcitonin; D002117:Calcitriol; D002118:Calcium