Pietro Palatroni

Comparative study by histochemical, biochemical, and histophotometrical methods of carbonic anhydrase activity in the stomach of various vertebrate classes

Histochemical, biochemical, and histophotometrical studies of carbonic anhydrase activity have been carried out on the stomach of the various vertebrate classes, in order to make functional comparisons. Our results on carbonic anhydrase activity of epithelial surface may be interpreted in favour of a protective role by the secretion of an alkaline fluid against damage due to intraluminal low pH values. As regards the presence of carbonic anhydrase in the different types of gastric glandular cells, in addition to the already known function of the enzyme in hydrochloric acid secretion in the oxyntic and oxyntic-peptic cells, we suggest an interpretation of carbonic anhydrase presence observed in many chief cells.

Regulatory activity of DNA-binding peptides on some metabolic pathways altered in aging

The Smith theory, which describes aging as a consequence of damage at DNA transcription level, suggested to us the opportunity of studying the possible action of DNA-binding peptides from calf thymus on old rats. We previously demonstrated that this peptidic fraction exerts a regulative control on transcriptional activities of DNA in cell and cell-free systems. In order to verify the possible action of these low molecular weight peptides we chose a large range of metabolic and structural parameters which are altered in aging. The results obtained indicate the following conclusions. Lipids. The lipid levels of old rat liver and serum are altered compared with those of young rats; the administration of peptidic fraction to old rats reverses the lipid alterations observed. Glucides. In old rat liver the presence of glycogen is very scanty or completely absent; the animals treated with the peptides show an amount and distribution of glycogen similar to that of adult normal rats. ATP. The peptidic fraction causes in the old rats a marked increase of blood ATP, bringing the level in the range of values determined in young rats. DNA, RNA, proteins. The total synthesis rate of DNA, RNA and proteins in old rat liver is not influenced by the DNA-binding peptides. Vice versa the nucleic acids from liver nuclei of old rats given peptidic fraction contain a greater RNA component compared to control old rats. This result is confirmed by the strong increase of transcriptional activity of DNA for RNA polymerase caused by administration of peptidic fraction to old rats. This increased DNA transcription can be interpreted as a partial recovery of DNA transcriptional capacity which evidently might imply a restoration of impaired metabolic systems. The histochemical and stereological analyses of liver cell compartments confirm the biochemical data.

Histochemical localization of carbonic anhydrase in Malpighian tubules ofCulex pipiens

Carbonic anhydrase (CA) activity has been localized histochemically by Hanssons method in Malpighian tubules ofCulex pipiens. The enzyme has been observed on membranes of the cytoplasmic inclusions of Malpighian cells; no CA activity has been found in other cytoplasmic structures. The possible meaning of the localization of the enzyme is discussed.

RENAL CARBONIC ANHYDRASE IN THE QUAIL COTURNIX COTURNIX JAPONICA. I, ACTIVITY AND DISTRIBUTION IN MALE AND FEMALE METANEPHROS

SummaryCarbonic anhydrase activity was studied in the quail metanephros by means of histochemical, histophotometrical and biochemical methods. Male and female samples were examined separately in order to show sex-related differences in enzyme activity and localization. The staining patterns revealed differential distribution of reaction product in the different, tubular segments. The initial portion of proximal tubules showed positivity on the brush border in female kidneys only.Extra situ investigations provided further evidence of sexual dimorphism resulting in higher values of enzyme activity for female than for male kidneys.In both sexes, marked staining was detected at the distal tubule level where histophotometric analysis confirmed the highest amount of reaction product. Moreover, the intracellular staining distribution at this site proved to be similar to that observed for mammalian proximal convoluted tubules.In the collecting ducts, a mosaic-like pattern was found with respect to both carbonic anhydrase staining and metachromatic properties.The functional significance of the presence of enzyme in the different renal tubules is discussed by comparison with the mammalian kidney. A model is proposed whereby the distal tubules represent the main sites of urinary acidification and bicarbonate reabsorption.

Renal carbonic anhydrase in the quail Coturnix coturnix japonica

SummaryCarbonic anhydrase activity was studied during development and regression of the quail mesonephros by in situ and extra situm investigation. A close correlation was noted between enzyme expression and tissue morphofunctional state. Carbonic anhydrase appears in early development; its highest activity is reached when the kidney is actively secreting, followed by a decrease concomitant with tissue involution. The main localization of the reaction product is the distal tubule showing strongly positive cells intercalated with clear, negative ones. In the functional organ, staining was found at the level of transitional and connecting segments and Wolffian duct. The comparison with the histochemical pattern of the quail metanephros suggests that the functional meaning of renal carbonic anhydrase might be the same both in transitory and in permanent kidney.

Cytochemical observations on lysosomal enzymes of rat lymphocytes at various ages

Light-microscopic cytochemical observations have been made in the presence of two lysosomal hydrolase (acid phosphatase and beta-glucuronidase) in the lymphocytes of rats of various ages. The results indicate a different behaviour for the two enzymes which has been discussed by comparing the variable percentages of small and large lymphocytes.

Differential inhibition by acetazolamide on carbonic anhydrase distribution in the quail kidney: a proposal for a membrane-bound isoenzyme

SummaryThe effects of different concentrations of acetazolamide, a specific carbonic anhydrase inhibitor, have been investigated in the quail kidney. The histochemical patterns, interpreted by means of quantitative analyses proved that 0.1 μm acetazolamide inhibited the enzyme activity in all the reactive tubular segments except for distal tubules. At this site, the reaction product disappeared from the cytoplasm but strong positivity persisted at the apical surface. The luminal staining was still present at higher inhibitor concentrations up to 0.8 μm acetazolamide. Under histophotometric analyses, the residual reactivity proved to be nearly the same at the increasing inhibitor concentrations assayed. The validity of the results was checked by similar investigations in other control tissues.On the basis of the properties known for carbonic anhydrase in mammalian kidney, we conclude that the luminal membrane staining in the quail distal tubules might be due to a carbonic anhydrase isoenzyme that is similar, both in affinity for acetazolamide and in intracellular localization, to the membrane-bound enzyme purified from mammalian proximal convoluted tubules.

Carbonic anhydrase activity in mammalian retina. Developmental aspects in altricial and precocial species

Carbonic anhydrase activity has been studied during retina development in 2 mammalian species, guinea pig and rat, which differ for birth time and gestational period as being precocial and altricial respectively. For both species, the definitive pattern of enzyme distribution corresponds to the localization of the reaction product in the Müller glial cells at the level of nucleus, perikaryon, lateral processes, and end-feet. Only in the rat retina, staining has been observed also in some amacrine cells. The results of either in situ or extra situm investigations showed that, according to tissue maturity, in the precocial species, the definitive expression of carbonic anhydrase is reached at birth time. In the altricial species, on the contrary, maturity is very delayed and may be recognized at only the 12th d of postnatal life. Present findings confirm that carbonic anhydrase is a marker for the maturity of the retinal glial cells.