Cardiorenal protection in experimental hypertension with renal failure: comparison between vasopeptidase inhibition and angiotensin receptor blockade

Recent updates on novel therapeutic targets of cardiovascular diseases

In recent times cardiovascular diseases (CVDs) are the leading cause of mortality universally, caused more or less 17.7 million casualties with 45% of all illnesses (except communicable ones) in 2015 as per World Health Organization (WHO). According to American National Center for Health Statistics, cardiac disorders are costliest. Moreover, health care expenditures related to cardiac disorders are anticipated to exceed than diabetes and Alzheimer's. Straining of reactive oxygen species with diminished neutralization & inflammation critically adds to atherosclerosis and also proceed to other cardiovascular diseases such as cardiac remodeling and myocardial infarction (MI). In the past few years, researchers revealed multiple drug targets from animal studies and evaluated them in the therapeutics of cardiac disorders, which offered exciting clues for novel therapeutic strategies. Although, only few newer agents approved clinically and actual approaches for treatment are lagging behind. Several novel drugs found effective for the treatment of hypertension, congestive heart failure, cardiac arrhythmia and angina pectoris. Detailed mechanism of action, basic and clinical pharmacology of all novel drugs has been discussed in this review.

Azilsartan causes natriuresis due to its sympatholytic action in kidney disease

The sympathoinhibitory mechanism of azilsartan was investigated in an adenine-induced chronic renal failure model. Azilsartan exerted an antihypertensive effect, though BP elevation induced by adenine was marginal. The creatinine value was significantly lower in the azilsartan group (AZ) than in the vehicle group (VEH); furthermore, proteinuria was suppressed, and sodium excretion was augmented in the AZ group. The low frequency (LF) of systolic BP was suppressed (VEH: 4.07 ± 2.67 mmHg² vs. AZ: 3.32 ± 1.93 mmHg² P < 0.001), and the spontaneous baroreflex gain (sBRG) was augmented (VEH: 1.04 ± 0.62ms/mmHg vs. AZ: 1.38 ± 0.69 ms/mmHg, P < 0.001) in AZ. There were no significant differences in ACE1 and ACE2 expression between the groups, which indicated that the action of azilsartan on these components of the intrarenal renin-angiotensin-aldosterone system was comparatively small. Although NHE3, NKCC, and ENaC expression was similar between the groups, NaCl cotransporter (NCC) expression was markedly suppressed by azilsartan (P < 0.05). Thus, in a mild chronic kidney disease (CKD) model with slight BP elevation, the sympatholytic effect of ARB might be expected, and azilsartan might exert its natriuretic effect by NCC suppression achieved by sympathoinhibitory activity.

Vasopeptidase Inhibition Corrects the Structure and Function of the Small Arteries in Experimental Renal Insufficiency

BACKGROUND

We studied whether vasopeptidase inhibition corrects the structure and function of the small arteries in experimental chronic renal insufficiency (CRI).

METHODS

After 5/6 nephrectomy (NX) surgery was performed on rats, there was a 14-week follow-up, allowing CRI to become established. Omapatrilat (40 mg/kg/day in chow) was then given for 8 weeks, and the small mesenteric arterial rings were investigated in vitro using wire and pressure myographs.

RESULTS

Plasma and ventricular B-type natriuretic peptide (BNP) concentrations were increased 2- to 2.7-fold, while systolic blood pressure (BP) increased by 32 mm Hg after NX. Omapatrilat treatment normalized the BNP and reduced the BP by 45 mm Hg in the NX rats. Endothelium-dependent vasorelaxation was impaired but the response to acetylcholine was normalized after omapatrilat treatment. Vasorelaxations induced by nitroprusside, isoprenaline and levcromakalim were enhanced after omapatrilat, and the responses were even more pronounced than in untreated sham-operated rats. Arterial wall thickness and wall-to-lumen ratio were increased after NX, whereas omapatrilat normalized these structural features and improved the strain-stress relationship in the small arteries; this suggests improved arterial elastic properties.

CONCLUSION

Omapatrilat treatment reduced BP, normalized volume overload, improved vasorelaxation and corrected the dimensions and passive elastic properties of the small arteries in the NX rats. Therefore, we consider vasopeptidase inhibition to be an effective treatment for CRI-induced changes in the small arteries.

Influence of renovascular hypertension on the distribution of vasoactive intestinal peptide in the stomach and heart of rats

Arterial hypertension is associated with serious dysfunction of the cardiovascular system and digestive system. Given the relevant role of vasoactive intestinal peptide (VIP) in the regulation of digestion process, control of blood pressure and heart rate as well as cardio- and gastro-protective character of the peptide, it appeared worthwhile to undertake the research aimed at immunohistochemical identification and evaluation of VIP-positive structures in the pylorus and heart of hypertensive rats. Up to now, this issue has not been investigated. The experimental model of hypertension in rats according to Goldblatt (two-kidney one clip model of hypertension) was used in the study. The experimental material (pylorus and heart) was collected in the sixth week of the study. VIP-containing structures were evaluated using immunohistochemical and morphometric methods. The analysis of the results showed a significant increase in the number of immunoreactive VIP structures and in the intensity of immunohistochemical staining in the stomach and in the heart of hypertensive rats. Our findings indicate that VIP is an important regulator of cardiovascular and digestive system in physiological and pathological conditions. However, to better understand the exact role of VIP in hypertension further studies need to be carried out.