ISSN:
1435-1803
Keywords:
Human coronary endothelial cells
;
patch-clamp
;
inwardly rectifying K+ currents
;
P2-purinoceptor
;
ATP
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The electrophysiological properties of human coronary endothelial cells (HCEC) of macro-and microvascular origin were studied using the whole-cell configuration of the patch-clamp technique. The membrane potential of confluent HCEC(−41.9±3.9 mV (mean±SEM, n=32) for macro-and −33.6±22.6 mV (n=64) for microvascular cells, respectively) was less negative than the K+ equilibrium potential. Inward currents of isolated cells at potentials below the K+ equilibrium potential were blocked by external Ba2+ (1 mM), inactivated due to time- and voltage-dependent block caused by external Na+, and their amplitudes were enhanced by increasing extracellular [K+]; these currents were identified as inwardly rectifying K+ currents. Some isolated cells displayed outwardly directed K+ currents which were abolished after replacement of Cs+ for K+ on both sides of the membrane. Voltage-dependent Ca2+ currents could not be observed in isolated HCEC. Hyperpolarizations induced by vasoactive agonists have been observed in some endothelial cells from different species. In contrast, extracellularly applied ATP (adenosine-5′-triphosphate) and ADP (adenosine-5′-diphosphate) at micromolar concentrations depolarized confluent HCEC, whereas adenosine had no effect on resting potentials (RP), indicating that the nucleotide-induced depolarizations were mediated via P2-purinoceptors. These depolarizations occurred even after replacement of N-methyl-D-glucamine for extracellular Na+, indicating that Ca2+-influx was involved. There were no marked differences in the electrophysiological properties between cells of macro-and microvascular origin.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00788535
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