ISSN:
1432-2013
Keywords:
Adenosine triphosphate
;
Caged-adenosine triphosphate
;
Potassium channel
;
Metabolism
;
Heart
;
Cardiac ventricle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract We have used ‘caged-ATP’ to investigate the kinetic behavior of KATP channels in ventricular cells from rat heart. In whole cells, loaded with ‘caged-ATP’, an increase of intracellular [ATP] following a UV light flash produced a decrease of KATP channel current that was too slow (τ ≈ 300 ms) to be explained by the expected timecourse of ATP release (τ ≈ 3 ms) and the time-course of channel blockade by ATP (τ ≈ 20 ms). In isolated membrane patches, caged-ATP itself caused partial blockade of KATP channels. Under these conditions, photorelease of ATP caused channel activity to decline further. The results suggest that caged-ATP can bind to the KATP channel but, on binding, decreases the open probability to a lesser extent than does ATP. Additionally, the observations indicate that for photolytically-generated ATP to bind to the channel, caged-ATP must first unbind (slowly) from the channel. We conclude that ‘caged-ATP’ is not fully caged with respect to its allosteric action on the KATP channel.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00373635
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