Pharmacological block of Ca2+-activated Cl−current in rat vascular smooth muscle cells in short-term primary culture

✍ Scribed by A. Baron; P. Pacaud; G. Loirand; C. Mironneau; J. Mironneau

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 592 KB
• Volume: 419
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370294

✦ Synopsis

Ca2+-activated C1-currents were studied in isolated cells from rat portal vein smooth muscle in shortterm primary culture using the whole-cell patch-clamp technique. C1-currents can be activated separately by Ca 2+ release from intracellular stores (in response to external applications of caffeine or noradrenaline) and by Ca 2+ influx through voltage-dependent Ca 2 + channels. The effects of several C1-channel blockers and of spironolactone (a substance known to reduce internal Ca 2+ loading) on both C1-and Ca 2+ currents were examined. Diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), anthracene-9-carboxylic acid (9-AC) and diphenylamine-2,2'-dicarboxylic acid (DPC) inhibited the CaZ+-activated C1-current (IC5o values between 16.5 and 306 gM) with no effects on the inward Ca 2 + current and on internal Ca 2+ loading (tested by measuring the Ca 2 +-activated K + current). These results indicate that the inhibition of C1-current by these compounds is due to a direct interaction with the C1-channel. In contrast, spironolactone inhibited both K + and C1-currents (ICso = 7.6 gM) by reducing the amount of Ca 2 + located in the internal stores, whereas the C1-current activated by Ca 2 + current through T-type Ca 2 + channels was unchanged. This preparation and the protocols developed in this study appears to be appropriate for analysis of substances interfering with C1-channels or intracellular Ca 2 + stores.