Intracellular free calcium concentration / force relationship in rabbit inferior vena cava activated by norepinephrine and high K+
✍ Scribed by Raouf A. Khalil; Cornelis Breemen
- Book ID
- 104745021
- Publisher
- Springer
- Year
- 1990
- Tongue
- English
- Weight
- 895 KB
- Volume
- 416
- Category
- Article
- ISSN
- 0031-6768
No coin nor oath required. For personal study only.
✦ Synopsis
The changes in isometric force and the underlying fluctuations in intracellular free calcium concentration ([Ca 2 +]i) were monitored simultaneously in thin sheets of rabbit inferior vena cava loaded with the fluorescent Ca z + indicator fura-2. In resting tissues bathed in physiological saline solution, the estimated [Ca2+]~ was approximately 105 nM. The ~-adrenergic agonist norepinephrine (10 gM) caused an initial rise in [Ca2+]i to 264 nM during force development, which dropped to 216 nM during force maintenance. The maintained norepinephrine-induced increase in force and [Ca2+]i was reversed in Ca2+-free (2 mM EGTA) solution. Membrane depolarization by high K + (80 mM) significantly increased [Ca2+]~ to 234nM. Compared to norepinephrine, high K + caused about the same steady-state increase in [Ca2+]~, but a smaller increase in force. [Ca 2 +]i/force curves were constructed at different concentrations of extracellular Ca 2 +, with either norepinephrine or high K + as a stimulant. The curve generated with norepinephrine was located to the left of that generated with high K +.