Ethanol perturbs receptor-operated cytosolic free calcium concentration signals in cultured rat hepatocytes.
OBJECTIVE
Studies of the acute effects of ethanol on hepatocellular free calcium concentration, [Ca2+]i, and on receptor-operated [Ca2+]i signals have produced conflicting results. The effects of ethanol on basal and receptor-operated [Ca2+]i signals in rat hepatocytes cultured on two different extracellular matrices were examined.


METHODS
[Ca2+]i was determined by digitized fluorescence microscopy and inositol 1,4,5-trisphosphate (Ins[1,4,5]P3) by high-performance liquid chromatography (HPLC).


RESULTS
Ethanol induced an increase in [Ca2+]i in hepatocytes cultured on collagen I but not on the more physiological substratum, matrigel. Compared with hepatocytes cultured on matrigel, cells on collagen I exerted less responsiveness and lower amplitude of [Ca2+]i signals to vasopressin or phenylephrine. The effects of ethanol on receptor-operated [Ca2+]i signals were examined in hepatocytes cultured on matrigel. Incubation of hepatocytes with physiologically attainable concentrations of ethanol (20-30 mmol/L) for 30 minutes to 48 hours perturbed epidermal growth factor, phenylephrine, and lower concentration (< or = 1 nmol/L) of vasopressin-induced [Ca2+]i signaling by reducing the amplitude and changing the pattern of [Ca2+]i signals. Alcohol induced-impairment of [Ca2+]i signaling was associated with decreased production of Ins(1,4,5)P3.


CONCLUSIONS
Alcohol does not itself evoke an increase in [Ca2+]i in hepatocytes cultured on matrigel but perturbs receptor-operated [Ca2+]i signaling. This is associated with and could be caused by impaired generation of Ins(1,4,5)P3.
Zhang
B H
BH
Storr Liver Unit, Department of Medicine, University of Sydney, Westmead Hospital, New South Wales, Australia.
Farrell
G C
GC
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000032:analysis* / Q000502:physiology*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003094:Collagen; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D004338:Drug Combinations; D004815:Epidermal Growth Factor / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D005109:Extracellular Matrix; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007797:Laminin; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D011509:Proteoglycans; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014667:Vasopressins / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D014667:Vasopressins; C059485:matrigel; D010656:Phenylephrine; D000431:Ethanol; D004815:Epidermal Growth Factor; D015544:Inositol 1,4,5-Trisphosphate; D003094:Collagen; D002118:Calcium