Effects Of Aerobic Exercise On Ca²⁺ Transport-related Protein Expression In Vascular Smooth Muscle Cells From SHR

Objective:Intracellular Ca2+plays an important role in the pathogenesis of hypertension. A variety of Ca2+-related proteins which are distributed broadly invascular smooth mucsle cells (VSMC) are closely related to hypertension-induced vascular remodeling. This study aims to investigate how low-intensity aerobic exercise affects Ca2+transport-related proteins in arteries from spontaneously hypertensive rats (SHR) and explore the Ca2+transport mechanisms underlying the beneficial effects on blood pressure induced by exercise training.Methods:Twelve-week-old male SHR rats were randomly divided into SHR sedentary group (SHR-SED, n= 12) and SHR exercise group (SHR-EX,40-50% VO2max, n= 12). Twelve age-matched WKY rats were used as normotensive control. Rats in exercise group were preformed with 8 week-treadmill exercise:O°slope, 15m/min,60 min/d,5 d/wk. After 8 weeks of aerobic exercise, systolic blood pressure (SBP) and heart rate (HR) were determined by an indirect tail-cuff method. Thoracic aorta and mesenteric artery were evaluated:1. Western blotting was performed to detect the protein expression of α1C subunits of L-type calcium channels (Cavl.2), inositol 1,4,5-triphosphate receptor 1 (IP3R1), sarcoplasmic reticulum Ca2+-ATP ase (SERCA2), and calsequestrin (CSQ); 2. ryanodine receptor 2 (RyR2) and its regulatory protein FKBP12.6, phospholamban (PLN) mRNA levels were tested by PCR.Results:(1) Compared with WKY group, basal SBP and HR in SHR-SED group were significantly higher (P<0.05), basal SBP and HR were significantly lower in SHR-EX group than those in SHR-SED group (P<0.05); (2) The protein expression of Cav1.2-α1C, IP3R1, CSQ in thoracic aorta and mesenteric arterial VSMCs from SHR-SED group were significantly increased (P<0.05), SERCA2 protein expression was significantly reduced (P<0.05) compared with WKY group; The protein expression of Cavl.2-α1C, IP3R1 and CSQ were significantly decreased in SHR-EX group than those in SHR-SED group (P<0.05), however, SERCA2 protein expression was significantly increased (P<0.05); (3) The mRNA levels of RyR2 in SHR-SED group were significantly higher than that in WKY group (P<0.05); the FKBP12.6 mRNA expression was significantly lower than that in WKY group (P<0.05); the PLN mRNA in SHR-SED mesenteric artery was significantly lower than that in WKY group (P<0.05), whereas no significant differences were observed in thoracic aorta (P>0.05) between SHR-SED and WKY; compared with SHR-SED group, the mRNA expression of RyR2 and FKBP12.6 in thoracic aorta and mesenteric artery in SHR-EX group had no significant change (P>0.05), while PLN mRNA expression showed a significant increase (P<0.05).Conclusions:These results indicate that arterial smooth muscle cells Ca2+ transport-related proteins altered, which is characterized by cell membrane Cay1.2 channel and sarcoplasmic reticulum Ca2+release channel RyR2 and IP3Rl upregulation and expression of sarcoplasmic reuculum calcium pump down regulation. Aerobic exercise can reduce blood pressure, decreased hypertension-induced Ca2+transport-related proteins pathological changes.