Role of cell volume in K+-induced Ca2+ signaling by rat adrenal glomerulosa cells.
The involvement of cell volume in the K+-evoked Ca2+ signaling was studied in cultured rat glomerulosa cells. Previously we reported that hyposmosis (250 mOsm) increased the amplitude of T-type Ca2+ current and, accordingly, enhanced the Ca2+ response of cultured rat glomerulosa cells to K+. In the present study we found that this enhancement is not influenced by the cytoskeleton-disrupting drugs cytochalasin-D (20 microM) and colchicine (100 microM). Elevation of extracellular potassium concentration ([K+]e) from 3.6 to 4.6-8.6 mM induced cell swelling, which had slower kinetics than the Ca2+ signal. Cytoplasmic Ca2+ signal measured in single glomerulosa cells in response to stimulation with 5 mm K+ for 2 min showed two phases: after a rapid rise reaching a plateau within 20-30 sec, [Ca2+]c increased further slowly by approximately one third. When 5 mM K+ was coapplied with elevation of extracellular osmolarity from 290 to 320 mOsm, the second phase was prevented. These results indicate that cell swelling evoked by physiological elevation of [K+]e may contribute to the generation of sustained Ca2+ signals by enhancing voltage-activated Ca2+ influx.
Makara
Judit K
JK
Department of Physiology and Laboratory of Cellular and Molecular Physiology, Semmelweis University Medical School and Hungarian Academy of Sciences, H-1444 Budapest, Hungary.
Koncz
Péter
P
Petheö
Gábor L
GL
Spät
András
A
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D048429:Cell Size / Q000502:physiology; D003078:Colchicine / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D015384:Zona Glomerulosa / Q000166:cytology* / Q000502:physiology*
D015638:Cytochalasin D; D011188:Potassium; D003078:Colchicine; D002118:Calcium