Human cytomegalovirus infection stimulates Cl-/HCO-3 exchanger activity in human fibroblasts.
The effects of human cytomegalovirus (HCMV) infection on Cl-/HCO-3 exchanger activity in human lung fibroblasts (MRC-5 cells) were studied using fluorescent, ion-sensitive dyes. The intracellular pH (pHi) of mock- and HCMV-infected cells bathed in a solution containing 5% CO2-25 mM HCO-3 were nearly the same. However, replacement of external Cl- with gluconate caused an H2DIDS-inhibitable (100 microM) increase in the pHi of HCMV-infected cells but not in mock-infected cells. Continuous exposure to hyperosmotic external media containing CO2/HCO-3 caused the pHi of both cell types to increase. The pHi remained elevated in mock-infected cells. However, in HCMV-infected cells, the pHi peaked and then recovered toward control values. This pHi recovery phase was completely blocked by 100 microM H2DIDS. In the presence of CO2/HCO-3, there was an H2DIDS-sensitive component of net Cl- efflux (external Cl- was substituted with gluconate) that was less in mock- than in HCMV-infected cells. When nitrate was substituted for external Cl- (in the nominal absence of CO2/HCO-3), the H2DIDS-sensitive net Cl- efflux was much greater from HCMV- than from mock-infected cells. In mock-infected cells, H2DIDS-sensitive, net Cl- efflux decreased as pHi increased, whereas for HCMV-infected cells, efflux increased as pHi increased. All these results are consistent with an HCMV-induced enhancement of Cl-/HCO-3 exchanger activity.
Department of Physiology, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania 19129, USA.
L M
LM
Maglova
W E
WE
Crowe
A A
AA
Altamirano
J M
JM
Russell
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D017920:Antiporters / Q000187:drug effects / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism; D002138:Calibration; D002460:Cell Line; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides / Q000378:metabolism; D003587:Cytomegalovirus / Q000502:physiology*; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000502:physiology / Q000821:virology; D005456:Fluorescent Dyes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006982:Hypertonic Solutions; D007700:Kinetics; D008168:Lung; D011804:Quinolines; D013050:Spectrometry, Fluorescence / Q000379:methods
D017920:Antiporters; D001639:Bicarbonates; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D005456:Fluorescent Dyes; D006982:Hypertonic Solutions; D011804:Quinolines; C078229:N-(6-methoxyquinolyl)acetoethyl ester; C067984:5-diethylamiloride; C018564:dihydro-DIDS; D000584:Amiloride; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid