Tension-voltage relations of single myocytes reflect Ca release triggered by Na/Ca exchange at 35 degrees C but not 23 degrees C

• DOI: 10.1152/ajpcell.1994.267.2.c623
• Publication Date: 2017-12-24T17:59:45Z
• Authors: M. Vornanen; N. Shepherd; G. Isenberg
• Keywords: Pipette; Tension (geology)

Contractile tension in response to 200-ms voltage-clamp pulses was measured isolated guinea pig ventricular cells conditioned constant Ca load. At 23 degrees C, the tension-voltage relation bell shaped, decaying from a maximum at +20 mV zero +100 mV, but 35 C it sigmoidal, with similar twitch tensions and mV. Tension reduced by ryanodine or caffeine abolished removal of just before test pulse. increased markedly as Na concentration patch pipette ([Na]p) varied between 0 20 mM. Cd (300 microM) blocked all potentials remained presence (29% control +2 100% mV). Cd-resistant began relax during clamp pulse (80 +/- 10 ms 140 12 Ni (3.6 mM) both slowed transients potentials. The results suggest that fast contractions due sarcoplasmic reticulum release can be triggered influx through either current (ICa) Na/Ca exchange those are much more temperature sensitive than ICa.