Renin angiotensin system and cardiac hypertrophy after sinoaortic denervation in rats

OBJECTIVE: The aim of this study was to evaluate the role of angiotensin I, II and 1-7 on left ventricular hypertrophy of Wistar and spontaneously hypertensive rats submitted to sinoaortic denervation. METHODS: Ten weeks after sinoaortic denervation, hemodynamic and morphofunctional parameters were analyzed, and the left ventricle was dissected for biochemical analyses. RESULTS: Hypertensive groups (controls and denervated) showed an increase on mean blood pressure compared with normotensive ones (controls and denervated). Blood pressure variability was higher in denervated groups than in their respective controls. Left ventricular mass and collagen content were increased in the normotensive denervated and in both spontaneously hypertensive groups compared with Wistar controls. Both hypertensive groups presented a higher concentration of angiotensin II than Wistar controls, whereas angiotensin 1-7 concentration was decreased in the hypertensive denervated group in relation to the Wistar groups. There was no difference in angiotensin I concentration among groups. CONCLUSION: Our results suggest that not only blood pressure variability and reduced baroreflex sensitivity but also elevated levels of angiotensin II and a reduced concentration of angiotensin 1-7 may contribute to the development of left ventricular hypertrophy. These data indicate that baroreflex dysfunction associated with changes in the renin angiotensin system may be predictive factors of left ventricular hypertrophy and cardiac failure.

NaCl plus chitosan as a dietary salt to prevent the development of hypertension in spontaneously hypertensive rats

The effect of NaCl plus 3% chitosan on the systolic blood pressure of spontaneously hypertensive rats (SHR) were evaluated and compared with NaCl plus KCl (NaCl, 49.36% + KCl 49.36%) and chitosan or NaCl treatment alone. In SHR, administration of NaCl plus chitosan (44 mM Na/day) for two months significantly decreased the systolic blood pressure greater than of NaCl plus KCl and NaCl alone. NaCl plus chitosan resulted, though not statistically significant, in decreased urinary Na+ excretion and decreased blood urea nitrogen levels. Urinary creatinine of NaCl plus chitosan was slightly decreased compared to 3 treated groups. Serum electrolytes levels, however, remained unchanged. The combination of NaCl and chitosan may be superior to the conventional use of NaCl plus KCl or NaCl alone in the prevention of hypertension. Even though these supplementary diets have demonstrated potential anti-hypertensive effects in the experimental animal model, further research is needed before any recommendations can be made.

Reduced plasma levels of angiotensin-(1-7) and renin activity in preeclamptic patients are associated with the angiotensin I- converting enzyme deletion/deletion genotype

The relationship between preeclampsia and the renin-angiotensin system (RAS) is poorly understood. Angiotensin I-converting enzyme (ACE) is a key RAS component and plays an important role in blood pressure homeostasis by generating angiotensin II (Ang II) and inactivating the vasodilator angiotensin-(1-7) (Ang-(1-7)). ACE (I/D) polymorphism is characterized by the insertion (I) or deletion (D) of a 287-bp fragment, leading to changes in ACE activity. In the present study, ACE (I/D) polymorphism was correlated with plasma Ang-(1-7) levels and several RAS components in both preeclamptic (N = 20) and normotensive pregnant women (N = 20). The percentage of the ACE DD genotype (60 percent) in the preeclamptic group was higher than that for the control group (35 percent); however, this percentage was not statistically significant (Fisher exact test = 2.86, d.f. = 2, P = 0.260). The highest plasma ACE activity was observed in the ACE DD preeclamptic women (58.1 ± 5.06 vs 27.6 ± 3.25 nmol Hip-His Leu-1 min-1 mL-1 in DD control patients; P = 0.0005). Plasma renin activity was markedly reduced in preeclampsia (0.81 ± 0.2 vs 3.43 ± 0.8 ng Ang I mL plasma-1 h-1 in DD normotensive patients; P = 0.0012). A reduced plasma level of Ang-(1-7) was also observed in preeclamptic women (15.6 ± 1.3 vs 22.7 ± 2.5 pg/mL in the DD control group; P = 0.0146). In contrast, plasma Ang II levels were unchanged in preeclamptic patients. The selective changes in the RAS described in the present study suggest that the ACE DD genotype may be used as a marker for susceptibility to preeclampsia.

Renin angiotensin aldosterone system and drug allergies complicated with hypotension.

It has been discussed in several studies that non-immunologic factors, such as renin angiotensin aldosterone system (RAAS) may play a role in the pathophysiology of anaphylaxis. This study aimed to determine whether RAAS plays a part in the fall in blood pressure during drug reactions or not. Twenty patients who experienced hypotension during drug reaction and 15 healthy volunteers were enrolled in this study. None of the patients in the study or control groups were under treatment with any drug that was capable of influencing to RAAS. Serum levels of angiotensin-I (A-I), angiotensin-II (A-II), angiotensin converting enzyme (ACE) and aldosterone were measured in both study and control groups. The Mann-Whitney U test was used to compare the results of the groups. There were no statistically significant differences between the groups with respect to A-I, A-II, ACE and aldosterone levels. It was concluded that a fall in blood pressure during drug reaction must be the result of mast cell mediator effects on the vascular wall rather than RAAS impairment.

Medición de la actividad de renina plasmática a niveles bajos: optimización del método / Measurement of low levels of plasma renin activity: a methodological improvement

Background: The present method to measure plasma renin activity is cumbersome and imprecise, factors that limit its clinical application. Aim: To assess the importance of blood sampling conditions and the usefulness of increasing incubation time to measure plasma renin activity at low levels. Patients and methods: Twenty hypertensive patients, 14 female, aged 14 to 76 years old, were studied. Two blood samples were obtained after a 10 min rest in the sitting position and after a 30 min rest in supine position. One blood sample, of each condition was sent lo the laboratory at room temperature and the other sample was sent refrigerated. Angiotensin I concentration was determined after 3 h of enzymatic incubation at 37°C and, in subjects with an activity of less than 1 ng/ml/h, after 18 h of incubation. Results: No significant differences in plasma renin activity were observed between the samples obtained with different rest times or different transportation methods. In people with low plasma renin activity, the 18 h enzymatic incubation reduced the lower detection from 0.3 to 0.014 ng/ml/h and the coefficient of variation from 14.4 to 3.2 percent. Conclusions: A simplified blood sampling method does not change plasma renin activity values, and tbe longer enzymatic incubation in people with low plasma renin activity improves both the sensitivitv and accuracy of the determination

effect of extracorporeal shock wave lithotripsy [ESWL] on angiotensin I, N-acetyl-B-glucosaminidase, urinary marker proteins, parathyroid hormone, pancreatic amylase and muscle injury enzyme markers

To detect the source of relevant acute intrarenal side effects after extracorporeal shock wave lithotripsy [ESWL], urinary excretion of highly specific marker proteins [alpha 1 and beta 2 microglobulin], as well as tubular enzyme N-acetyl-beta-D glucosaminidase [NAG] were analyzed before and after ESWL. A highly significant increase in urinary marker proteins [alpha 1 M and beta 2 M] and urinary enzyme NAG were recognized immediately following ESWL. Alpha 1 M and NAG returned to their pre-ESWL levels but beta 2 M remained high till day 30. Plasma renin activity-PRA [angiotensin I] was highly significantly elevated immediately after ESWL and remained high after 1 month. The parathyroid hormone [PTH], CK-MB were highly significant elevated. Gamma glutamyl transferase [GGT], alanine aminotransferase [ALT], aspartate aminotransferase[AST], alkaline phosphatase[ALP] and pancreatic amylase were significantly higher than normal immediately after ESWL but all to their pre-ESWL values after 1 month

Plasma renin activity in normal healthy volunteers: effect of physiological variables.

Plasma renin activity was determined in hundred normal subjects of either sex (M = 65, F = 35, age range 2-70 yr) using Angiotensin-I test kits. The effect of various physiological variables viz, age, sex, posture and salt intake was determined. The basal values for PRA ranged from 1.19 +/- 0.09 ng/ml/hr for males and 1.02 +/- 0.12 ng/ml/hr for females in erect posture. In contrast high basal supine PRA was noticed in subjects on low salt diet, which showed a significant increase in erect posture. A marked decrease in PRA with advancing age in both the sexes with significantly low values at higher age range was noticed. Captopril produced an insignificant effect on PRA and BP in salt replete supine state, whereas in salt deplete state there was a significant rise in both the parameters.