Biomedical subjects

C Iribar

Publications and source records attributed to C Iribar.

8 recordsLinked to original sources

PubMed1995

Decrease in cytosolic Aspartyl-aminopeptidase but not in Alanyl-aminopeptidase activity in the frontal cortex of the aged rat.

To test the neurotoxic hypothesis of excitatory amino acids, we evaluated the possible contribution to the free acidic amino acid pool of Aspartyl-aminopeptidase activity in the frontal cortex of adult (3 month old) and aged rats (3 groups of animals aged 26, 29 and 33 months). Aspartyl-aminopeptidase activity showed a significant decrease in the oldest rats (29 and 33 months old) whereas the activity of Alanyl-aminopeptidase, an unspecific enzyme, did not change with age. These data invalidate the idea that excess free acidic amino acids are released by aminopeptidases in the aged rat but do provide evidence of age-related changes in this enzymatic activity. The possible implications of our findings for general alterations in protein degradation are discussed.

Aging↗

PubMed1993

Regional distribution of soluble and membrane-bound aminopeptidase activities in rat brain.

Soluble and membrane-bound aminopeptidase activities in 11 regions of the rat brain were assayed using L-Leucine-2-naphthylamide as a substrate. In addition, two metabolic enzymatic activities were compared: lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotransferase activities were significantly lower in cortical than in subcortical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did not differ between cortical areas and the rest of the zones studied. However, although no wide regional differences were found for the other enzymatic activities, membrane-bound aminopeptidase varied markedly across brain regions: a fivefold difference was observed between zones such as parietotemporal cortex and medulla. The differential distribution of this enzymatic activity is consistent with the hypothesis that it could be responsible for the enzymatic inactivation of some neuroactive peptides.

Aminopeptidases↗

PubMed1989

Postnatal development of aminopeptidase (arylamidase) activity in rat brain.

Changes in the activities of Leu- and Arg-arylamidase in rat frontal and parietal cortices and the subcortical area (including thalamus, hypothalamus, and striatum) were examined in the 2nd, 4th, 8th, 12th, and 24th weeks of life. Average levels found in the subcortical region were greater than those in the cortical areas. The most marked changes in enzymatic activity in the course of brain development were found in the subcortical structure. Leu-arylamidase activity increased from the 2nd week up to the 8th week, returning to the 2nd week level at the 12th and 24th weeks. The maximum levels of Arg-arylamidase activity were found at the 4th and 8th weeks. These data suggest that proteolytic activity is involved in the postnatal development of rat brain.

Aminopeptidases↗

PubMed1988

Aminopeptidase activity is asymmetrically distributed in selected zones of rat brain.

Levels of soluble aminopeptidase (AP), measured as arylamidase activity using L-Leucine-2-Naphthylamide (Leu-2-NA) as substrate, were determined in the soluble fraction of eleven zones of rat brain. Results showed that AP activity is asymmetrically distributed in frontal cortex and hypothalamus with both left sides having significantly higher levels of AP activity, respectively, than the right sides. Simultaneously, the activities of lactate dehydrogenase (LDH) and glutamate-oxalacetate aminotransferase (GOT) were measured in the same cerebral regions; no significant difference was recorded in these activities between either side of the rat brain in any of the zones studied. Provided that aminopeptidases are involved in the degradation of some endogenously released neuropeptides, the results suggest a new mode of expression of cerebral lateralization.

Aminopeptidases↗

PubMed1988

[Is the renin-angiotensin system implicated in the hypertensive effect of a water-soluble tissue extract?].

A deproteinized hydrosoluble splenic extract, which produces a hypertensive effect, injected in rats intravenously is described. The pressure action is very similar to the synthetic angiotensin II, and the (Sarcosine1-Isoleucine8)--angiotensin II, a competitive antagonist, produced partial inhibition of both responses. There were no significant differences between control and experimental rats in the plasmatic levels of angiotensin II, aldosterone and ADH. Therefore, the splenic extract does not seem to release these hormones included in the renin-angiotensin pathway. Significant Angiotensin II levels were detected in the splenic material. These results support the view that forty per cent of the pressure action is due to Angiotensin II present in the extract.

Aldosterone↗

PubMed1987

[Inhibiting effect of (sarcosine-1-isoleucine-8)-angiotensin II in anesthesized rats].

The peptidic sequence (Sarcosine-1-Isoleucine-8)-Angiotensin II has been demonstrated to be an in vitro specific and competitive antagonist of the Angiotensin II action. The present results show it to be a competitive antagonist also in vivo since pA2 values are similar, always reaches a 100% response on increasing the Angiotensin II dose, and when relating log (DR-1) and log dose of agonist, the slope is very near to one (0.925).

Anesthesia↗

PubMed1986

Asymmetrical distribution of aminopeptidase activity in the cortex of rat brain.

The levels of soluble aminopeptidase (AP) activity were measured in the right and left frontal (FC), parietotemporal (PTC) and occipital (OC) cortex of male albino rat brains. The results showed more AP activity in the left cortex than in the right. Analyzing these results further, we found that the differences are significant for frontal cortex but not for parietotemporal nor occipital cortex. However, 76% of the rats were left-predominant for AP activity in the 3 cortical areas studied.

Aminopeptidases↗

PubMedDate not supplied

[Interhemispherical study of the activities of aminopeptidases, lactate dehydrogenase and glutamate-oxaloacetate transaminase in the rat brain].

Aminopeptidase activity has been assayed from both soluble and membrane bound fractions in eleven regions of the left and right hemispheres of the rat brain, using L-leucine-2-naphthylamide as substrate. Two other metabolic enzymes, lactate dehydrogenase and glutamate-oxalacetate aminotransferase activities were simultaneously determined in the same areas. When individual zones of the left hemisphere were compared with its corresponding right zones, soluble aminopeptidase activities were significantly higher in left frontal cortex and left hypothalamus than in right frontal cortex and right hypothalamus, respectively. No other significant differences were found neither in the remaining areas nor for the other enzymatic activities between both brain hemispheres.

Aminopeptidases↗