angiotensin-i and imidapril

The objective of this article is to explore the role of imidapril on pulmonary hypertension induced by low ambient temperature in broiler chickens.. Ninety chickens were randomly divided into three groups (n = 30): a control group, a low-temperature group and an imidapril group. Chickens in the low-temperature group and imidapril group were exposed to low ambient temperature from 14 days of age until 45 days of age; chickens in the imidapril group were gavaged with imidapril 3 mg/kg once daily for 30 days. The pulmonary arterial pressure, main pulmonary arterial diameter and pulmonary arterial wall thickness were measured, and lung tissue ACE, ACE2 mRNA expression, proliferating cell nuclear antigen (PCNA)-positive cells and Ang II, Ang (1-7) concentration were evaluated.. The pulmonary arterial pressure was higher, the main pulmonary arterial diameter was wider and the pulmonary arterial wall was thicker in the low-temperature group than those in the control group and the imidapril group. ACE mRNA and PCNA-positive cells increased significantly in the low-temperature group compared with the control group and imidapril group; lung tissue Ang II concentration in the low-temperature group was higher, but Ang (1-7) content was lower than that in the control group and imidapril group.. Imidapril provides a protective effect on pulmonary hypertension induced by low ambient temperature in broiler chickens.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Arterial Pressure; Chickens; Cold Temperature; Hypertension, Pulmonary; Imidazolidines; Lung; Peptide Fragments; Peptidyl-Dipeptidase A; Poultry Diseases; Proliferating Cell Nuclear Antigen; Pulmonary Artery

This study explored the effect of imidapril on the right ventricular remodeling induced by low ambient temperature in broiler chickens. Twenty-four broiler chickens were randomly divided into 3 groups (n = 8), including the control group, low temperature group, and imidapril group. Chickens in the control group were raised at normal temperature, whereas chickens in the low temperature group and imidapril group were exposed to low ambient temperature (12 to 18°C) from 14 d of age until 45 d of age. At the same time, chickens in the imidapril group were gavaged with imidapril at 3 mg/kg once daily for 30 d. The thickness of the right ventricular wall was observed with echocardiography. The BW and wet lung weight as well as weight of right and left ventricles and ventricular septum were measured. Both wet lung weight index and right ventricular hypertrophy index were calculated. Pulmonary arterial systolic pressure was assessed according to echocardiography. The expression of ACE and ACE2 mRNA in the right ventricular myocardial tissue was quantified by real-time PCR. Proliferating cell nuclear antigen-positive cells were detected by immunohistostaining. The concentration of angiotensin (Ang) II and Ang (1-7) in the right ventricular myocardial tissue was measured with ELISA. The results showed that right ventricular hypertrophy index, wet lung weight index, pulmonary arterial systolic pressure, expression of ACE mRNA in the right ventricular tissue, Ang II concentration, and the thickness of the right ventricular wall in the low temperature group increased significantly compared with those in the control group and imidapril group. The ACE2 mRNA expression increased 36%, whereas Ang (1-7) concentration decreased significantly in the low temperature group compared with that in the control group and imidapril group. In conclusion, imidapril inhibits right ventricular remodeling induced by low ambient temperature in broiler chickens.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animal Husbandry; Animals; Chickens; Cold Temperature; Gene Expression Regulation; Heart Ventricles; Housing, Animal; Imidazolidines; Peptide Fragments; Peptidyl-Dipeptidase A; Ventricular Remodeling

It has been suggested that proangiotensin-12 (proang-12), a novel angiotensin peptide recently discovered in rat tissues, may function as a component of the tissue renin-angiotensin system (RAS). To investigate the role of proang-12 in the production of angiotensin II (Ang II), we measured its plasma and tissue concentrations in Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, with and without RAS inhibition. The 15-week-old male WKY and SHR rats were left untreated or were treated for 7 days with 30 mg kg(-1) per day losartan, an angiotensin receptor blocker, or with 20 mg kg(-1) per day imidapril, an angiotensin-converting enzyme (ACE) inhibitor. Both treatments increased renin activity and the concentrations of angiotensin I (Ang I) and Ang II in the plasma of WKY and SHR rats, but neither affected plasma proang-12 levels. In contrast to the comparatively low level of proang-12 seen in plasma, cardiac and renal levels of proang-12 were higher than those of Ang I and Ang II. In addition, despite activation of the RAS in the systemic circulation, tissue concentrations of proang-12 were significantly reduced following treatment with losartan or imidapril. Similar reductions were also observed in the tissue concentrations of Ang II in both strains, without a reduction in Ang I. These results suggest that tissue concentrations of proang-12 and Ang II are regulated independently of the systemic RAS in WKY and SHR rats, which is consistent with the notion that proang-12 is a component of only the tissue RAS.

Topics: Angiotensin I; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Blood Pressure; Body Weight; Imidazolidines; Kidney; Losartan; Male; Myocardium; Organ Size; Peptide Fragments; Radioimmunoassay; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renin; Renin-Angiotensin System

The ability of angiotensin I (Ang I) and II (Ang II) to induce directly protein degradation in skeletal muscle has been studied in murine myotubes. Angiotensin I stimulated protein degradation with a parabolic dose-response curve and with a maximal effect between 0.05 and 0.1 microM. The effect was attenuated by coincubation with the angiotensin-converting enzyme (ACE) inhibitor imidaprilat, suggesting that angiotensin I stimulated protein degradation through conversion to Ang II. Angiotensin II also stimulated protein breakdown with a similar dose-response curve, and with a maximal effect between 1 and 2.5 microM. Total protein degradation, induced by both Ang I and Ang II, was attenuated by the proteasome inhibitors lactacystin (5 microM) and MG132 (10 microM), suggesting that the effect was mediated through upregulation of the ubiquitin-proteasome proteolytic pathway. Both Ang I and Ang II stimulated an increased proteasome 'chymotrypsin-like' enzyme activity as well as an increase in protein expression of 20S proteasome alpha-subunits, the 19S subunits MSS1 and p42, at the same concentrations as those inducing protein degradation. The effect of Ang I was attenuated by imidaprilat, confirming that it arose from conversion to Ang II. These results suggest that Ang II stimulates protein degradation in myotubes through induction of the ubiquitin-proteasome pathway. Protein degradation induced by Ang II was inhibited by insulin-like growth factor and by the polyunsaturated fatty acid, eicosapentaenoic acid. These results suggest that Ang II has the potential to cause muscle atrophy through an increase in protein degradation. The highly lipophilic ACE inhibitor imidapril (Vitortrade mark) (30 mg kg(-1)) attenuated the development of weight loss in mice bearing the MAC16 tumour, suggesting that Ang II may play a role in the development of cachexia in this model.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Cachexia; Cell Culture Techniques; Imidazolidines; Male; Mice; Muscle Fibers, Skeletal; Muscle Proteins; Muscle, Skeletal; Neoplasms; Proteasome Endopeptidase Complex; Ubiquitin

The effects of a new angiotensin-converting enzyme (ACE) inhibitor, imidapril hydrochloride ((-)-(4S)-3-[(2S)-2- [[(1S)-1-ethoxycarbonyl-3-phenylpropyl]amino]propionyl]- 1-methyl-2-oxoimidazolidine-4-carboxylic acid hydrochloride, imidapril, TA-6366, CAS 89396-94-1) and of its active metabolite, 6366 A (CAS 89371-44-8) on renal function were studied in anesthetized dogs and compared to the effects of enalapril and its active metabolite, enalaprilat. Intravenous (i.v.) administration of 6366 A at 30 micrograms/kg strongly inhibited angiotensin I-induced renal vasoconstrictive and pressor responses. 6366 A promptly lowered blood pressure and renal vascular resistance, and caused clear increases in renal blood flow and glomerular filtration rate. It also increased urine volume and urinary excretion of sodium and chloride. These renal effects were also produced by intraduodenal (i.d.) administration of 2 mg/kg of imidapril. However, the effects of i.d. imidapril began later, developed gradually and reached a plateau after 2 to 3 h. Enalaprilat (30 micrograms/kg i.v.) and enalapril (2 mg/kg i.d.) had renal effects similar to 6366 A and imidapril. In conclusion, the ACE inhibitor imidapril has beneficial effects on renal function via its active metabolite, and the effects appear to be essentially identical to those of enalapril.

Topics: Anesthesia; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Animals; Dogs; Enalapril; Enalaprilat; Female; Imidazoles; Imidazolidines; In Vitro Techniques; Injections, Intravenous; Male; Renal Circulation

Effects of imidapril hydrochloride ((-)-(4S)-3-[(2S)-2-[[(1S)-1- ethoxycarbonyl-3-phenylpropyl]amino]propionyl]-1-methyl-2- oxoimidazolidine-4-carboxylic acid hydrochloride, imidapril, TA-6366, CAS 89396-94-1), a new prodrug type angiotensin converting enzyme (ACE) inhibitor, and 6366 A (CAS 89371-44-8), an active metabolite of imidapril, on isolated vascular preparations were studied. 6366 A inhibited angiotensin I (AT-I)-induced contraction of the rabbit thoracic aorta at 3 x 10(-10) mol/l or more and augmented bradykinin (BK)-induced relaxation of the dog renal artery precontracted with prostaglandin F2 alpha PGF2 alpha at 10(-9) mol/l or more, whereas imidapril at 10(-7) mol/l did not affect these responses. However, 6366 A, like imidapril, had no effect on angiotensin II (AT-II), norepinephrine, serotonin-, KCl- and PGF2 alpha-induced contractions. The inhibitory effect of 6366 A on AT-I-induced contraction was attenuated by denudation of the endothelium, but it was still maintained even after washing out the aorta that had been previously exposed to the medium containing 6366 A. This suggests that 6366 A persistently inhibits the angiotensin I converting enzyme located preferentially in the endothelium. Therefore, the antihypertensive action of imidapril is mainly attributable to the vasodilation through the inhibitory effects of 6366 A on AT-II synthesis and BK degradation in the vasculature.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta, Thoracic; Bradykinin; Dinoprost; Dogs; Endothelium, Vascular; Female; Imidazoles; Imidazolidines; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Norepinephrine; Potassium Chloride; Rabbits; Serotonin