Effects of anoxia on K and Ca currents in isolated guinea pig cardiocytes

✍ Scribed by M. Friedrich; K. Benndorf; M. Schwalb; Hj. Hirche

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 309 KB
• Volume: 416
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370244

✦ Synopsis

Whole cell currents were measured in isolated cardiocytes of guinea pig under anoxic conditions (pO 2 <0.5 torr). After 2 to 32 (mean 11.2) minutes of anoxia, time independent outward currents developed gradually which had a linear current-voltage relation between -100 and +20 mV and reversed at the resting potential of the cells (-82 to -90 mV). After 20 to 170 (mean 38) seconds, the amplitude of these outward currents saturated (3.6+0.5 nA at +10 mV, n=23). Reoxygenation within one minute after the appearance of the first extra outward currents led in most cells (>90%) to their complete disappearance in 2 to 4 (mean 2.87, n=15) seconds. Ca currents were not affected at the time when the first extra outward currents occurred. It is concluded that (i) the anoxia-induced outward current is carried by K + ions probably through KAT P channels which open at intracellular ATP concentrations below 1 mmol/I (Noma and Shibasaki 1985) and (ii) this degree of ATP depletion does not affect normal Ca channel function.