title: [Intervention of systolic pressure and left ventricular hypertrophy in rats under cold stress].
abstract: OBJECTIVE
  To investigate the effects of different drugs on systolic blood pressure (SBP) and left ventricular hypertrophy (LVH) in spontaneously hypertensive rats under cold stress.
  
  
  METHODS
  A total of 40 male spontaneously hypertensive rats aged 10 weeks (160~200 g) were given adaptive feeding for 7 days at a temperature of 20±1°C and then randomly divided into control group, cold stress group, metoprolol group, amlodipine group, and benazepril group, with 8 rats in each group. SBP, body weight, and heart rate were measured once a week. After the rats were sacrificed by exsanguination, left ventricular weight (LVW) was measured, and left ventricular weight index (LVWI; mg/g) was calculated. Radioimmunoassay was used to measure the concentrations of endothelin-1 (ET-1) and angiotensin-II (Ang-II) in plasma and myocardium, and the chemical method was used to measure the concentrations of nitric oxide (NO) in plasma and myocardium. RT-PCR was used to measure the mRNA expression of endothelin-A receptor.
  
  
  RESULTS
  Compared with the cold stress group, all medication groups showed significant reductions in SBP since week 5 (P<0.05). The cold stress group showed a significant increase in LVWI compared with the control group (3.38±0.27 mg/g vs 2.89±0.19 mg/g, P<0.05). The amlodipine group showed a significant reduction in LVWI compared with the cold stress group (2.98±0.28 mg/g vs 3.38±0.27 mg/g, P<0.05). The cold stress group showed a significant reduction in plasma NO concentration compared with the control group (104.9±19.5 μmol/L vs 129.3±17.8 μmol/L, P<0.05) ; compared with the cold stress group, all the medication groups showed significant increases in blood NO concentration (P<0.05). The cold stress group showed a significant increase in myocardial ET-1 concentration compared with the control group (6.3±1.5 pg/100 mg vs 4.5±1.9 pg/100 mg, P<0.05) ; compared with the cold stress group, the amlodipine group showed a significant reduction in myocardial ET-1 concentration (4.4±1.0 pg/100 mg vs 6.3±1.5 pg/100 mg, P<0.05). The cold stress group had significantly higher mRNA expression of endothelin-A receptor than the control group (0.86±0.23 vs 0.45±0.16, P<0.01) ; compared with the cold stress group, the amlodipine group showed a significant reduction in the mRNA expression of endothelin-A receptor (0.41±0.14 vs 0.86±0.23, P<0.01).
  
  
  CONCLUSIONS
  Amlodipine can reduce the increase in SBP and inhibit LVH in spontaneously hypertensive rats under cold stress.
authors: Department of Emergency Center, Huai'an Hospital Affiliated of Xuzhou Medical College, Huai'an 223002, China.
authors: C F
authors: CF
authors: Sun
authors: S G
authors: SG
authors: Wang
authors: Y G
authors: YG
authors: Peng
authors: Y
authors: Y
authors: Shi
authors: Y P
authors: YP
authors: Du
authors: G X
authors: GX
authors: Shi
authors: T
authors: T
authors: Wen
authors: Y K
authors: YK
authors: Wang
authors: H
authors: H
authors: Su
mesh_terms: D000804:Angiotensin II; D000818:Animals; D001552:Benzazepines; D001794:Blood Pressure; D003080:Cold Temperature; D019332:Endothelin-1; D006973:Hypertension; D017379:Hypertrophy, Left Ventricular; D008297:Male; D009206:Myocardium; D051381:Rats; D011918:Rats, Inbred SHR; D013312:Stress, Physiological
chemical_list: D001552:Benzazepines; D019332:Endothelin-1; D000804:Angiotensin II; C044946:benazepril