Arterial injury models for coronary artery disease have demonstrated an enhanced expression and function of either the endothelin(A) or endothelin(B) (ET(A) or ET(B)) receptor subtype. We hypothesized that organ culture would enhance the physiological function of ET receptors in the porcine right coronary artery. Arteries were either cold stored (4°C) or organ cultured (37°C) for 4 days. After 4 days, the artery was either 1) sectioned into rings to measure the ET-1-induced isometric tension response (3 x 10-10-3 x 10-7 M), or 2) enzymatically dispersed and the isolated smooth muscle cells imaged using fura-2 to measure the myoplasmic calcium (Ca(m)) response to 3 x 10-8 M ET-1 (~EC50). Isometric tension and Ca(m) to ET-1 were measured in the absence and presence of bosentan (nonselective ET(A) or ET(B) receptor antagonist), BQ788 (ET(B)-selective antagonist), and BQ123 (ET(A)-selective antagonist). Compared with cold storage, organ culture induced a 2-fold increase in tension development (3 x 10-7 M ET-1) and Ca(m) (3 x 10-8 M ET-1), which was inhibited with bosentan, thus confirming the enhanced responses to ET-1 were due to ET receptor activation. BQ123 also inhibited the enhanced contraction and Ca(m) responses to ET-1. In contrast, BQ788 failed to inhibit tension development and Ca(m) responses to ET-1 in organ culture and cold storage. Sarafotoxin 6C (ET(B) agonist) failed to elicit an increased Ca(m) response in organ culture compared with cold storage. Our results indicate the increased tension development and Ca(m) responses to ET-1 in organ culture are attributable to ET(A) receptors, and not ET(B) receptors.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Pharmacology and Experimental Therapeutics|
|State||Published - Jan 1 2000|
ASJC Scopus subject areas
- Molecular Medicine