Biomedical subjects

E Mangiarua

Publications and source records attributed to E Mangiarua.

7 recordsLinked to original sources

PubMed1986

Vascular renin-like activity in aorta and mesenteric artery of the rat.

Vascular renin-like enzymatic activity (VRLA) has been measured in the artery wall of control and experimental rats. The following groups have been studied: 1-normal salt diet; 2-high salt diet; 3-low salt diet; 4-bilateral nephrectomy (Nx); 5-sham operated for Nx. VRLA was evaluated in the aorta (ARLA) and in the mesenteric arteries (MRLA). Blood samples were obtained for plasma renin activity (PRA) determination. High salt diet decreased PRA, ARLA and MRLA whereas low salt diet increased PRA, did not change ARLA and decreased MRLA. PRA was almost undetectable in Nx animals while ARLA showed a 40% reduction and MRLA was unchanged in these animals. These results would indicate that the changes in PRA induced different variations in the renin-like content of the aorta and the mesenteric artery. The differences could be mainly due to two factors: 1) the capacity of the vascular tissue to bind circulating renin and 2) the capacity of each tissue to synthetize renin-like material in situ.

Animals↗

PubMed1985

Renin-like activity in vascular tissue of DOC-salt hypertensive rats.

The presence of isorenin active at the physiological pH was investigated in DOC-salt hypertensive rats. The effect of chronic captopril treatment was analyzed in similarly treated animals and in control rats. The levels of the plasma (PRA) and vascular enzyme (VRLA) were compared with those of untreated control animals. DOC-salt administration was maintained during 4 or 8 weeks. Captopril was given in the drinking fluid beginning 4 days before DOC-salt treatment. Renin-like activity was measured in the aorta and mesenteric arteries. DOC-salt treatment reduced PRA to almost undetectable levels while aorta renin-like enzyme only decreased to 50% at 4 weeks and was not changed at 8 weeks. Isorenin levels in the mesenteric artery did not show any significant variation. Captopril did not prevent the increase in blood pressure due to DOC-salt administration and it induced a significant increase in PRA and in VRLA in control rats whereas it did not increase either - enzyme in DOC-salt treated rats. In summary these results confirm the existence of a vascular isorenin and suggest that both binding and local synthesis of the enzyme could take place in the arterial wall.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1983

Vascular structural changes in the artery wall of unilateral nephrectomized rats.

Wet and dry weight, concentration and total amount of nucleic acids and proteins, and incorporation of tritiated thymidine were measured in the arteries of rats after 7 and 15 days of unilateral nephrectomy, sham operation and in control animals. Arteries of uninephrectomized rats showed increased wet and dry weight, increased DNA and protein content after 7 and 15 days and a higher rate of tritiated thymidine uptake after the first week. These results suggest an early proliferative process in the arteries of unilateral nephrectomized rats.

Animals↗

PubMedDate not supplied

Renin-like activity in the rat brain during the development of DOC-salt hypertension.

Levels and distribution of an angiotensin-forming enzyme, active at the physiological pH (isorenin), were determined in the central nervous system of 24 rats treated with 25 mg/kg of deoxycorticosterone (DOC) subcutaneously, twice a week, plus saline to drink during 30 days and in 14 control animals. Different areas of the brain were excised and homogenized. Renin activity and concentration were determined by incubation of the supernatant of each homogenate at pH 7.2 alone and in the presence of an excess of renin substrate. The angiotensin generated was measured by radioimmunoassay. Concentration of the renin-like enzyme was significantly higher in the posterior hypophysis and in the brain stem of the experimental group; isorenin activity was higher in the hypothalamus, cerebral cortex, cerebellum, and brain stem of the DOC-salt-treated rats than in the control rats. Changes in the angiotensin-forming enzyme in the central nervous system of experimental animals, active at physiological pH, suggest that this isorenin system may play a role in the physiological response to DOC-salt in the rat. The significance of the brain isorenin system in the regulation of blood pressure requires further analysis.

Animals↗

PubMedDate not supplied

Vascular structural changes in DOC-salt hypertensive rats.

Vascular alterations in DOC-salt hypertensive rats 10 and 30 days after the onset of the treatment were studied and compared with those from rats receiving only DOC, rats drinking salt, and control rats. Wet weight and absolute amounts of deoxyribonucleic acid (DNA) and ribonucleic acid (RnA) of the artery wall were significantly increased in DOC-salt rats 10 and 30 days after the onset of the treatment. RNA/DNA and protein/DNA ratios were similar in all the experimental groups. The arteries of DOC-salt animals incorporated tritiated thymidine at a higher rate 10 days after beginning the treatment, while the uptake was similar in all the animals at the end of the experimental period. These results would indicate that, in this type of hypertension, the increase in artery mass is mainly the result of cellular hyperplasia, which is active during the early phase of the process; afterward the vascular wall reaches a new steady state characterized by a greater number of cells and no further cell proliferation.

Animals↗

PubMedDate not supplied

Angiotensinogen concentration in the cerebrospinal fluid in different experimental conditions in the rat.

Angiotensinogen is the most important component of the renin-angiotensin system present in the cerebrospinal fluid (CSF) of the rat. Its physiological significance as well as its origin have not been clearly elucidated. In this experiment we have examined plasma renin activity (PRA) and plasma and CSF angiotensinogen concentration under the following experimental conditions in male rats of the Wistar strain: 1) adrenalectomy (Adx) 4 days prior to sample collection; controls were sham Adx animals; 2) nephrectomy (Nx) 48 hours before blood and CSF collection; controls were sham Nx rats; 3) DOC-salt treatment (Cortexon depot, 50 mg/kg.s.c. twice a week) plus saline to drink was given during 4 weeks; controls were intact rats; 4) DOC-salt plus captopril: captopril (100 mg/kg/day) in the drinking fluid was added to the treatment of experimental and control animals of Group 3; 5) two-kidney, two clip hypertension: silver clips placed in both renal arteries 8 weeks before samples collection; control: sham-operated rats; 6) water deprivation: rats deprived of water for 5 days; controls: intact rats; 7) peripheral sympathectomy: 6-hydroxydopamine (6-HODA) injected s.c. from birth until 16 weeks of age, adrenodemedullectomy and adrenal denervation performed at 8 weeks; controls were vehicle-injected animals. Determination of angiotensinogen concentration in plasma and CSF was accomplished by incubation of the samples with excess hog renin. The angiotensin I released as well as PRA were evaluated using an specific radioimmunoassay technique. PRA was significantly increased by Adx, captopril treatment, and water deprivation, and was almost suppressed by Nx, DOC-salt, and DOC-salt plus captopril treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗

PubMedDate not supplied

Further studies on the development of two-kidney, two clip Goldblatt hypertension in 6-hydroxydopamine-treated rats.

The development of two-kidney, two clip Goldblatt hypertension (2K2C) in the rat seems to be unaffected by chemical sympathectomy with 6-hydroxydopamine (6-HODA) and adrenal demedullation. Since this treatment only partially depletes vascular norepinephrine (NE) content, we evaluated the degree of sympathectomy achieved with the 6-HODA treatment and the structural vascular changes in treated and untreated animals. Litters of male Wistar rats were divided in two groups: 6-HODA-treated (6-HODA) animals (group 1) were injected with 6-HODA since the day of birth until the end of the experiment; control group (CG) animals (group 2) received the vehicle solution. When rats reached about 250 g, a silver clip (0.25 mm width) was placed on both renal arteries in half of them in each group; a sham operation was performed on the rest of the animals. Adrenal demedullation and denervation was performed in all 6-HODA animals. Blood pressure was followed weekly by the tail cuff method for 7 weeks. At the 8th week, Silastic cannulas were placed in the carotid artery and jugular vein in all the animals. Pressor responses to tyramine (0.05 and 0.1 mg), angiotensin (10, 40 and 160 ng), and norepinephrine (NE) (25, 100 and 400 ng) and the hypotensive effect of prazosin (1 mg/kg) were determined in the conscious rats. The pressor effect of carotid occlusion was registered 24 hours later. Animals were sacrificed, and the heart and artery weight as well as the nucleic acids and alkali soluble proteins content in the vascular wall were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗