Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
De Paoli, P; Cerbai, E; Koidl, B; Kierchengast, M; Sartiani, L; Mugelli, A.
Selectivity of different calcium antagonists on T- and L-type calcium currents in guinea-pig ventricular myocytes.
Pharmacol Res. 2002; 46(6):491-497
Doi: 10.1016%2FS1043661802002360
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- Co-Autor*innen der Med Uni Graz
- Koidl Bernd
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- Abstract:
- Both L- and T-type calcium channels are present in the heart. In cardiac myocytes L-type calcium channels are blocked by the classical calcium channel blockers, while T-type calcium channels are thought to be insensitive to these drugs and to be selectively blocked by mibefradil. We aimed to compare the T/L calcium channel blocking selectivity of several calcium channel blockers by evaluating their effects on both components evoked in the same cell from a holding potential corresponding to the normal physiological value (-90mV). Currents were recorded in single patch-clamped guinea-pig ventricular myocytes, superfused with a Na(+)- and K(+)-free solution to abolish overlapping currents. Two dihydropyridines (amlodipine and lacidipine), verapamil diltiazem and mibefradil were tested; for each compound concentrations equieffective on L-type Ca(2+) current were used. All calcium channel blockers, at concentrations blocking less than 30% of L-type Ca(2+) current, inhibited a significant amount of T-type Ca(2+) current, varying from 0.8% (diltiazem) to 28% (mibefradil). We calculated for each compound the T/L ratio. As expected, mibefradil showed the highest T selectivity; lacidipine and diltiazem resulted to be L selective. Verapamil and amlodipine were not selective. Thus, the calcium channel blockers can be differentiated on the basis of their T/L selectivity.
- Find related publications in this database (using NLM MeSH Indexing)
- Action Potentials - drug effects
- Animals - drug effects
- Calcium Channel Blockers - pharmacology
- Calcium Channels, L-Type - physiology
- Calcium Channels, T-Type - physiology
- Guinea Pigs - physiology
- Heart Ventricles - cytology
- Male - cytology
- Myocytes, Cardiac - drug effects
- Find related publications in this database (Keywords)
- calcium channel blockers
- L-type calcium antagonists
- T-type calcium antagonists
- guinea-pig ventricular myocytes
- electrophysiology