Vascular dysfunction as target organ damage in animal models of hypertension. Int J Hypertens. 2012;2012:187526. [PMID: 22518280 PMCID: PMC3296220 DOI: 10.1155/2012/187526]

Effect of aminoguanidine on cardiovascular responses and survival time during blood loss: A study in normotensive and deoxycorticosterone acetate-salt hypertensive rats

Introduction:

Hemorrhagic shock causes more circulatory disturbances and mortality in hypertensive than normotensive subjects. In the late phase of hemorrhagic shock, nitric oxide (NO) overproduction leads to vascular decompensation. In this study, we evaluated the effect of inducible NO synthase (iNOS) inhibitor, aminoguanidine (AG), on hemodynamic parameters and serum nitrite concentration in decompensated hemorrhagic shock model in normotensive and hypertensive male rats.

Materials and Methods:

Twenty-four male rats were divided into hypertensive and normotensive groups (n = 12 each). Hypertension was induced by subcutaneous injection of deoxycorticoesterone acetate (DOCA), 30 mg/kg in uninephrectomized rats. Decompensated hemorrhagic shock was induced by withdrawing blood until the mean arterial pressure (MAP) reached 40 mmHg. After 120 min, each group was assigned to aminguanidine (100 mg/kg) and control group. Hemodynamic parameters were monitored for next 60 min. Blood samples were taken before and after shock period and 60 min after treatment. Survival rate was monitored for 72 h.

Results:

Infusion of AG in normotensive animals caused a transient increase in MAP and increase of heart rate, whereas it did not affect those parameters in hypertensive animals. Hemorrhagic shock caused a significant rise in serum nitrite concentration in normotensive and hypertensive rats and infusion of AG did not significantly change it in both groups. No significant differences observed in survival rate between AG-treated and not treated groups.

Conclusion:

It seems that inhibition of iNOS with AG does not have beneficial effects on hemodynamatic parameters and survival rate during decompensated hemorrhagic shock in normotensive and hypertensive animals.

Exercise training in hypertension: Role of microRNAs

Hypertension is a complex disease that constitutes an important public health problem and demands many studies in order to understand the molecular mechanisms involving his pathophysiology. Therefore, an increasing number of studies have been conducted and new therapies are continually being discovered. In this context, exercise training has emerged as an important non-pharmacological therapy to treat hypertensive patients, minimizing the side effects of pharmacological therapies and frequently contributing to allow pharmacotherapy to be suspended. Several mechanisms have been associated with the pathogenesis of hypertension, such as hyperactivity of the sympathetic nervous system and renin-angiotensin aldosterone system, impaired endothelial nitric oxide production, increased oxygen-reactive species, vascular thickening and stiffening, cardiac hypertrophy, impaired angiogenesis, and sometimes genetic predisposition. With the advent of microRNAs (miRNAs), new insights have been added to the perspectives for the treatment of this disease, and exercise training has been shown to be able to modulate the miRNAs associated with it. Elucidation of the relationship between exercise training and miRNAs in the pathogenesis of hypertension is fundamental in order to understand how exercise modulates the cardiovascular system at genetic level. This can be promising even for the development of new drugs. This article is a review of how exercise training acts on hypertension by means of specific miRNAs in the heart, vascular system, and skeletal muscle.

Slight increase in urinary albumin excretion within the normal range predicts incident hypertension in a community-based Japanese population: the Takahata study

Recent studies have suggested that urine albumin excretion in the high normal range predicts hypertension. However, the relationship between urinary albumin excretion in spot urine and incident hypertension remains unclear in the general Japanese population. To clarify this relationship, we conducted a cohort study in a community-based population of 412 normotensive individuals without diabetes and renal insufficiency and examined the incidence of hypertension using the urinary albumin-to-creatinine ratio (UACR) at baseline. Incident hypertension was defined as new-onset systolic blood pressure ⩾ 140 mm Hg and/or diastolic blood pressure ⩾ 90 mm Hg and/or the use of anti-hypertensive drugs. During the follow-up period (median, 6.7 years), 133 subjects (32.3%) newly developed hypertension. The incidence of hypertension increased with an increase in baseline UACR (20.4% for UACR <5 mg g(-1), 34.0% for 5-9.9 mg g(-1) UACR and 40.4% for 10-29.9 mg g(-1), P=0.002). Multivariate logistic regression analysis, after adjustment for possible confounders, showed that UACR 5-9.9 mg g(-1) and 10-29.9 mg g(-1) were independent risks for incident hypertension compared with UACR <5 mg g(-1) (odds ratio (OR) 2.15, 95% confidence interval (CI) 1.16-4.10 and OR 2.67, 95% CI 1.36-5.38, respectively). Subgroup analysis revealed that subjects with increased UACR (⩾ 5 mg g(-1)) had a higher risk of incident hypertension than did those with low UACR (<5 mg g(-1)), irrespective of their backgrounds (age, sex, smoking, alcohol consumption, obesity and urinary sodium excretion). In conclusion, this study showed that a slight increase in urinary albumin excretion might predict incident hypertension in a community-based Japanese population.