Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Schmid, R; Seydl, K; Baumgartner, W; Groschner, K; Romanin, C.
Trypsin increases availability and open probability of cardiac L-type Ca2+ channels without affecting inactivation induced by Ca2+.
Biophys J. 1995; 69(5):1847-1857
Doi: 10.1016/S0006-3495(95)80055-X
[OPEN ACCESS]
Web of Science
PubMed
FullText
FullText_MUG
Google Scholar
- Co-Autor*innen der Med Uni Graz
- Groschner Klaus
- Altmetrics:
- Dimensions Citations:
- Plum Analytics:
- Scite (citation analytics):
- Abstract:
- The patch-clamp technique was employed to investigate the response of single L-type Ca2+ channels to the protease trypsin applied to the intracellular face of excised membrane patches from guinea pig ventricular myocytes. Calpastatin and ATP were used to prevent run-down of Ca2+ channel activity monitored with 96 mM Ba2+ as charge carrier in the presence of 2.5 microM (-)-BAYK 8644. Upon application of trypsin (100 micrograms/ml) channel activity was enhanced fourfold and remained elevated upon removal of trypsin, as expected of a proteolytic, irreversible modification. The trypsin effect was not mediated by a proteolytic activation of protein kinases, as evidenced by the insensitivity of this effect to protein kinase inhibitors. Trypsin-modified Ca2+ channels exhibited the usual run-down phanomenon upon removal of calpastatin and ATP. In ensemble average currents trypsin-induced changes of channel function are apparent as a threefold increase in peak current and a reduction in current inactivation. At the single channel level these effects were based on about a twofold increase in both Ca2+ channels' availability and open probability. Neither the actual number of channels in the patch nor their unitary conductance as well as reversal potential was changed by trypsin. The Ca(2+)-induced inactivation was not impaired, as judged by a comparable sensitivity of trypsin-modified Ca2+ channels to intracellular Ca2+. Similarly, trypsin treatment did not affect the sensitivity of Ca2+ channels to phenylalkylmine inhibition. The observed alterations in channel function are discussed in terms of possible structural correlates.
- Find related publications in this database (using NLM MeSH Indexing)
- Adenosine Triphosphate - pharmacology
- Animals -
- Biophysical Phenomena -
- Biophysics -
- Calcium - metabolism
- Calcium Channels - classification Calcium Channels - drug effects Calcium Channels - metabolism
- Calcium-Binding Proteins - pharmacology
- Gallopamil - analogs and derivatives Gallopamil - pharmacology
- Guinea Pigs -
- Heart Ventricles - metabolism
- Intracellular Fluid - metabolism
- Ion Transport - drug effects
- Kinetics -
- Membrane Potentials - drug effects
- Muscle, Smooth - drug effects Muscle, Smooth - metabolism
- Myocardium - metabolism
- Protein Kinases - metabolism
- Trypsin - pharmacology