Calpastatin and nucleotides stabilize cardiac calcium channel activity in excised patches.
The activity of single L-type Ca2+ channels is rapidly lost (run-down) when contact between the membrane and cytosol is interrupted. We have now achieved the stabilization of cardiac Ca2+ channel activity of guinea-pig ventricular myocytes by using either cytosol or defined components added to excised patches. The endogenous protease inhibitor, calpastatin, together with nucleotides, ATP + GTP, was found to prevent run-down as effectively as cardiac cytosolic solution. These results suggest the involvement of proteolysis by calpain in run-down of channel activity and enable the study of cardiac Ca2+ channel regulation with free access to both sides of the membrane.
Romanin
C
C
Institute for Biophysics, University of Linz, Austria.
Grösswagen
P
P
Schindler
H
H
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004553:Electric Conductivity; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009206:Myocardium / Q000378:metabolism*
D015220:Calcium Channels; D002135:Calcium-Binding Proteins; D015853:Cysteine Proteinase Inhibitors; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C033668:calpastatin; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate