Flash photolysis of intracellular caged GTP gamma S increases L-type Ca2+ currents in cardiac myocytes
| Autor: | R. Z. Kozlowski, A. M. Brown, V. W. Twist, Trevor Powell |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
GTP'
Physiology G protein Heart Ventricles Guinea Pigs chemistry.chemical_element Guanosine In Vitro Techniques Calcium chemistry.chemical_compound Physiology (medical) Animals Patch clamp Evoked Potentials Photolysis Heart Thionucleotides Glutathione Dithiothreitol Kinetics chemistry Biochemistry Guanosine 5'-O-(3-Thiotriphosphate) Second messenger system Biophysics Flash photolysis Calcium Channels Guanosine Triphosphate Cardiology and Cardiovascular Medicine Intracellular |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 261:H1665-H1670 |
| ISSN: | 1522-1539 0363-6135 |
| DOI: | 10.1152/ajpheart.1991.261.5.h1665 |
| Popis: | L-type calcium currents were recorded from isolated ventricular myocytes using standard patch-clamp methods. Rapid release of photolabile guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), tetralithium salt, by flash photolysis of intracellular caged-GTP gamma S increased the magnitude of the L-type calcium current: an effect independent of the ultraviolet flash per se or the production of photolytic by-products. This increase in calcium current was markedly reduced by intracellularly applied guanosine 5-O-(thiodiphosphate), trilithium salt or by an excess of GTP gamma S. It is therefore likely that rapid release of GTP gamma S intracellularly in the absence of an agonist can, via a G protein-mediated mechanism, cause L-type calcium current activation. In the presence of Rp-adenosine 3,5-mono-thionophosphate (Rp-cAMP), photoreleased GTP gamma S results in a transient and much reduced increase in the amplitude of the L-type calcium current. We conclude that activation of Gs coupled to adenylate cyclase and ultimately cAMP-dependent phosphorylation may be primarily responsible for L-type channel activation, although a fast membrane-delimited (direct) pathway, not involving cytoplasmic second messengers, may also contribute to this effect. |
| Databáze: | OpenAIRE |
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