[Effect of exercise stress on cigarette smoking induced downregulation of BKca and Kv1.5 expression in pulmonary arterial smooth muscle cells of rats].
OBJECTIVE
To investigate the effect of exercise stress on chronic cigarette smoking induced downregulation of large conductance calcium-activated potassium channel (BKca) and voltage-dependent delayed rectifier potassium channel (Kv1.5) expression in pulmonary arterial smooth muscle cells of rats.


METHODS
Rats were divided into three groups: the normal control group, the smoking control group and the smoking + exercise group. The plasma cortisol level, the potassium channel expression and the pathological changes in lung tissue were determined with HE staining, the immunohistochemistry and the in-situ hybridization.


RESULTS
(1) In the smoking + exercise group, the plasma cortisol level was determined immediately after exercise [(1528.7 +/- 469.7) ng/L] and was higher than that determined before exercise [(672.4 +/- 235.7) ng/L] (P < 0.01); (2) The HE staining showed that the chronic pulmonary inflammatory response in the smoking control group was severe while it was mild in the smoking + exercise group; (3) The mRNA and protein expression (OD value) of BKca in the smoking control group (mRNA: 0.2206 +/- 0.0415 for big artery and 0.3935 +/- 0.1378 for small artery; protein: 0.2634 +/- 0.1219 for big artery and 0.0995 +/- 0.0851 for small artery) were less than those in the normal control group. The mRNA expression of BKca in the smoking + exercise group (OD value) (0.5022 +/- 0.1134 for big artery and 0.6408 +/- 0.2135 for small artery) was higher than that in the smoking control group; (4) The mRNA and protein expression of Kv1.5 in the smoking control group (OD value) (mRNA: 0.9354 +/- 0.3290 for big artery and 0.5012 +/- 0.1170 for small artery; protein: 1.1112 +/- 0.3310 for big artery and 0.4736 +/- 0.1250 for small artery) were less than those in the normal control group. The protein expression of Kv1.5 in the smoking + exercise group (0.7445 +/- 0.2690) in small artery was higher than that in the smoking control group.


CONCLUSIONS
Proper exercise stress can decrease inhibition effect of the chronic smoking on the expression of potassium channel BKca and Kv1.5, which perhaps partly results from exercise induced increase of cortisol secretion.
Ye
Hong
H
Department of Pathophysiology, Tongji Medical College, Hua Zhong University of Science and Technology, Pulmonary Laboratory of Ministry of Health of China, Wuhan 430030, China.
Wu
He-hua
HH
Du
Liang
L
Jin
Si
S
Hu
Qinq-hua
QH
Liu
Sheng-yuan
SY
Wang
Di-xun
DX
D000818:Animals; D015536:Down-Regulation; D006854:Hydrocortisone / Q000097:blood; D051666:Kv1.5 Potassium Channel / Q000096:biosynthesis* / Q000235:genetics; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D008297:Male; D009068:Movement / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D015221:Potassium Channels / Q000096:biosynthesis* / Q000235:genetics; D011651:Pulmonary Artery / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012907:Smoking / Q000009:adverse effects*
C494842:Kcnma1 protein, rat; D051666:Kv1.5 Potassium Channel; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D015221:Potassium Channels; D012333:RNA, Messenger; D006854:Hydrocortisone