ISSN:
1432-2013
Keywords:
Key words Patch clamp
;
Calcium channel
;
Run-down
;
ATP
;
Cardiac myocytes
;
Cytoplasm
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The role of adenosine triphosphate (ATP) in the regulation of L-type Ca2+ channel activity was investigated in inside-out patches from guinea-pig ventricular cells, in which the Ca2+ channel activity had been reprimed by application of cytoplasm from bovine heart. Passing the cytoplasm through a diethylaminoethyl (DEAE)-sepharose column or heating at 60°C for 20 min attenuated the induction Ca2+ channel activity to 6–13% of that in the preceding cell-attached patch. Addition of 10 mM MgATP to the cytoplasm greatly improved the potency of cytoplasm in restoring Ca2+ channel activity (to 83 ± 22%, mean ± SE). This effect of MgATP was also produced, although with lower potency, by K2ATP (61 ± 20%) or 5′-adenylylimidodiphosphate (AMP-PNP, 39 ± 7%), a non-hydrolyzable ATP analogue, suggesting that hydrolysis of ATP is not required for the stimulatory effect on channel activity. A non-specific protein kinase inhibitor H8 (50–100 μM) did not inhibit the effect of cytoplasm + MgATP on channel activity, suggesting the involvement of a pathway independent of phosphorylation. We conclude that ATP regulates Ca2+ channel activity in dual pathways: one with, and the other without, protein phosphorylation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004240050314
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