Long-term regulation of contractility and calcium current in smooth muscle

Summary, in English

Longitudinal smooth muscle strips from guinea pig ileum were cultured in vitro for 5 days, and the relationship between extracellular Ca2+ and force in high-K+ medium was evaluated. In strips cultured with 10% fetal calf serum (FCS), this relationship was shifted to the right (50% effective concentration changed by 2-3 mM) compared with strips cultured without FCS. The shift was prevented by inclusion of verapamil (1 microM) during culture and mimicked by ionomycin in the absence of FCS. The intracellular Ca2+ concentration ([Ca2+]i) during stimulation with high-K+ solution or carbachol was reduced after culture with FCS, whereas the [Ca2+]i-force relationship was unaffected. Cells were isolated from cultured strips, and whole cell voltage-clamp experiments were performed. Maximum inward Ca2+ current (10 mM Ba2+), normalized to cell capacitance, was almost three times smaller in cells isolated from strips cultured with FCS. Culture with 1 microM verapamil prevented this reduction. These results suggest that increased [Ca2+]i during culture downregulates Ca2+ current density, with associated effects on contractility.

• Author: Maria Gomez; Karl Swärd
• Department/s: Vascular Physiology
• Publishing year: 1997
• Language: English
• Pages: 1714-1720
• Publication/Series: American Journal of Physiology: Cell Physiology
• Volume: 273
• Issue: 5
• Links: http://ajpcell.physiology.org/cgi/content/full/273/5/C1714
• Document type: Journal article
• Publisher: American Physiological Society
• Topic: Physiology
• Keywords: fura 2; verapamil; patch clamp; ionomycin; tissue culture
• Status: Published
• Research group: Vascular Physiology
• ISBN/ISSN/Other: ISSN: 1522-1563