Table 1.

Dimensional characteristics of cannulated coronary arterioles

	n	Maximal Diameter, μm	Preconstriction, %	ET-1, nM
Nonoccluded
Sedentary	46	129 ± 4	60 ± 3	0.27 ± 0.02
Exercise-trained	40	134 ± 5	62 ± 3	0.26 ± 0.02
Collateral-dependent
Sedentary	44	135 ± 6	58 ± 3	0.30 ± 0.03
Exercise-trained	44	133 ± 4	63 ± 2	0.27 ± 0.03

Values are means ± SE; n, number of arterioles. %Preconstriction, percentage of maximal diameter to which arterioles were preconstricted; ET-1, concentration of endothelin-1 required to obtain %preconstriction. No significant differences exist.