ABSTRACT
This study analyzes outward currents in freshly isolated goat chondrocytes patched in the whole cell mode. Capacitance tracings were recorded from the cells by the time domain method. The average capacitance was 6.33 pF ±2.15pF (Mean±SD, n=60). The range was 2.7 pF to 11.2 pF. A family of outward currents was seen when the cell was depolarized from –70 mV to +70 mV in 10 mV increments. The current density at +60 mV varied from 125 pA/pF to 2410 pA/pF. The currents were inhibited by 10 mM tetraethylammonium chloride (TEA) and the current-voltage profile suggests that these are voltage gated K+ channels. The currents were also recordable in a chloride-free external solution, thereby proving that these currents are not chloride currents. There was no evidence of voltage-gated sodium channels in these cells.
ABSTRACT
This is a concise review of important calcium-transporters on the sarcolemma and organellar membranes of myocardial cells, and their functional roles in cell physiology. It briefly addresses L and T type calcium channels, store-operated calcium channel (SOC), sodium-calcium exchanger (NCX), and the plasma membrane calcium ATPase (PMCA) on the sarcolemma, ryanodine receptor (RyR), IP3 receptor (IP3R) and the sarcoplasmic reticulum (SR) calcium ATPase (SAERCA) on the SR membrane and their contributions to contraction and rhythm-generation. Several agonists and blockers for every transporter that are commonly used in research, and those with therapeutic applications have also been discussed.