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. Author manuscript; available in PMC: 2012 Dec 23.
Published in final edited form as: J Appl Physiol (1985). 2004 Feb 20;97(1):310–316. doi: 10.1152/japplphysiol.01400.2003

Figure 3.

Figure 3

Comparison of Ca2+-sensitivity of collateral-dependent LCX and nonoccluded LAD arterial rings during KCl-induced membrane depolarization. A. Representative traces showing simultaneous measures of tension and Cai during exposure to noncumulative, increasing concentrations of KCl. Coronary arterial rings were superfused with KCl for 5 min, followed by 5-min recovery in normal PSS and subsequent exposure to a higher KCl concentration. B. Evaluation of tension as a function of Cai (fura-2 ratio) revealed that the collateral-dependent LCX developed significantly more tension per unit change in fura-2 ratio compared with the nonoccluded LAD (EC50, LAD=1.66±0.13, LCX=1.36±0.07 fura-2 ratio units). C. Control experiments examining Ca2+ sensitivity in nonoccluded animals demonstrated no significant regional differences (LAD vs. LCX) in tension development as a function of fura-2 ratio in response to increasing KCl concentrations (EC50, LAD=1.54±0.17, LCX=1.70±0.05 fura-2 ratio units). Values are means ± SE of the number of animals in parentheses.