Effects of chronic exercise on calcium signaling in rat vascular endothelium.
Chronic exercise enhances endothelium-dependent vasodilating responses. To investigate whether this is due to a change in endothelial Ca(2+) signaling, we examined intracellular Ca(2+) concentration ([Ca(2+)](i)) level in rat aortic endothelium in response to acetylcholine (ACh) or ATP. Four-week-old male Wistar rats were divided into control and exercise groups. The exercised animals ran on a treadmill at a moderate intensity for 60 min/day, 5 day/wk, for 10 wk. Rat aortas were then excised and loaded with fura 2. After the aortas were mounted on a flow chamber, these specimens were observed under an epifluorescence microscope equipped with ratio-imaging capability. Our results showed that 1) chronic exercise increased both ACh- and ATP-induced [Ca(2+)](i) responses; 2) ACh induced heterogeneous [Ca(2+)](i) elevation in individual endothelial cells; and 3) the exercise effect on ACh-evoked endothelial [Ca(2+)](i) elevation was inhibited by the Ca(2+) influx blocker SKF-96365, by a Ca(2+)-free buffer, or by high concentrations of extracellular K(+). We conclude that chronic exercise increases ACh-induced [Ca(2+)](i) elevation in rat aortic endothelium in situ, possibly by facilitating Ca(2+) influx.
Chu
T F
TF
Department of Physiology, National Cheng-Kung University Medical College, Tainan, Taiwan 701, Republic of China.
Huang
T Y
TY
Jen
C J
CJ
Chen
H I
HI
D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009043:Motor Activity / Q000502:physiology*; D009994:Osmolar Concentration; D010805:Physical Conditioning, Animal / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D000255:Adenosine Triphosphate; D000109:Acetylcholine; D002118:Calcium