Biomedical subjects

R Recchioni

Publications and source records attributed to R Recchioni.

35 records · Page 2Linked to original sources

PubMed1990

Voltage gating of Ca2(+)-activated potassium channels in human lymphocytes.

The effect of membrane potential on Ca2+ activated K+ channels was studied on human peripheral lymphocytes. Membrane potential was monitored using bisoxonol and flow cytometry. 1 mM Ca2+ in the presence of 2 microM ionomycin depolarized the control cell population, while 100 microM Ca2+ caused hyperpolarization. However 1 mM Ca2+ had a hyperpolarizing effect on previously partially depolarized cells. Potassium channel blockers did not influence the depolarization, while they inhibited the hyperpolarization. Based on the experimental evidence a voltage gating of Ca2+ activated K+ channels is suggested.

Calcium↗

PubMed1990

Antioxidant enzymes in erythrocytes from old and diet restricted old rats.

Diet restriction, prolonging the lifespan of rodents, represents an interesting model for gerontological studies. We analyzed the activity of antioxidant enzymes, Superoxide Dismutase, Catalase and Glutathione Peroxidase in erythrocytes from young, old and old food restricted Wistar rats. Diet restriction was applied feeding the animals on every-other-day schedule starting from the age of 3.5 months. The age-dependent decrease of Catalase and Glutathione Peroxidase activities was prevented by food restriction, whereas Superoxide Dismutase activity was not influenced either by aging and dietary intervention. Present results support the hypothesis that diet restriction increases the protection of cell structure against the peroxidative damage, preserving the activity of antioxidant enzymes.

Aging↗

PubMed1990

Diet restriction decreases the membrane microviscosity of cerebellar membranes of old female Wistar rats.

The microviscosity of cerebellar membranes from female Wistar rats during aging and subsequent to diet restriction has been investigated. Diet restriction was applied feeding the animals on every-other-day schedule starting from the age of 3.5 months. Undernutrition increased the lifespan of the animals and retarded the appearance of the age-dependent increase of microviscosity of cerebellar membranes.

Aging↗

PubMed1989

Ligand and voltage gated sodium channels may regulate electrogenic pump activity in human, mouse and rat lymphocytes.

Bretylium tosylate - a sodium channel opener - resulted in an increase of membrane potential of depolarized human, rat and mouse T and B lymphocytes. Flow cytometric membrane potential measurements with bis-oxonol revealed that the above hyperpolarizing effect was amiloride, ouabain, tetrodotoxin, azide and temperature sensitive. The effect showed an absolute dependence on the extracellular sodium but it was insensitive to the extracellular Ca2+ level. The voltage gating of the effect can be eliminated by either an increase of the extracellular potassium concentration or low doses of veratrin. The existence of a voltage and ligand gated sodium channel is suggested in the plasma membrane of all kinds of lymphocytes. The hyperpolarization is explained by an increased activity of the electrogenic sodium-potassium ATP-ase. Induced opening of such sodium channels may regulate the electrogenic pump activity and indirectly cell activation.

Amiloride↗

PubMedDate not supplied

Food restriction in female Wistar rats. I. Survival characteristics, membrane microviscosity and proliferative response in lymphocytes.

The effect of food restriction on the survival characteristics, membrane microviscosity and proliferative response in lymphocytes of female Wistar undernourished rats has been evaluated. Diet restriction was applied starting from the age of 3.5 months by feeding the animals on an every-other-day schedule (EOD). Diet restricted animals showed an increase of both mean, median and maximal life span as compared to the rats fed ad libitum (AL). Analyzing the survival curves by a parametric model, it emerged that undernutrition increased the individual resistance to environmental insults. In particular, it could be speculated that the positive influence was more pronounced in individuals with the lowest physiological capacities. The membrane microviscosity of lymphocytes was lower in EOD animals as compared to the AL ones even if one assumes a decrease in body temperature of 1-2 degrees C in EOD groups. The improvement of membrane microviscosity due to diet restriction may in part explain the improvement of proliferative response of lymphocytes from EOD groups.

Journal Article↗

PubMedDate not supplied

Food restriction in female Wistar rats. II. Beta-adrenoceptor density in the cerebellum and in the splenic lymphocytes.

The effect of diet restriction, applied on an every-other-day schedule from 3.5 months of age on, has been investigated on the beta-adrenoceptor density in the cerebellum and in the splenic lymphocytes of old female Wistar rats. Comparing animals 6 months and 24 months old fed ad libitum, a 75% age-dependent reduction in specific binding of the agonist dihydroalprenolol was observed in cerebellar membrane preparations, while the beta-adrenoceptor density of lymphocytes remained unaltered. Diet restriction induced a partial recovery of the age-related decrease of this parameter in the cerebellum without affecting the receptor density of lymphocytes. Present results suggest that undernutrition delays the appearance of those alterations related to aging.

Journal Article↗

PubMedDate not supplied

Food restriction in female Wistar rats. III. Thermotropic transition of membrane lipid and 5'-nucleotidase activity in hepatocytes.

The effect of diet restriction was measured on the anisotropy parameter of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 5'-nucleotidase enzyme activity in liver plasma membrane preparates. Diet restriction was applied to rats 3.5 months old on an every-other-day schedule (EOD) and the rats were killed at the age of 28-29 months. Six months and 24 months rats, fed ad libitum (AL), were used as controls. The Arrhenius plots of anisotropy parameter of liver membranes from young, old AL and old EOD animals exhibited well defined breakpoints at 16.3 degrees C, 19.5 degrees C and 16.7 degrees C, respectively. The breakpoint temperature of 5'-nucleotidase activity was lower in samples from young rats as compared to those from old AL rats, whereas no difference was observed comparing young and EOD fed rats. Present results support the hypothesis that diet restriction modifies lipid composition of liver plasma membranes in such a way that the appearance of age-dependent alterations is delayed.

Journal Article↗

PubMedDate not supplied

Diet restriction, body temperature and physicochemical properties of cell membranes.

This paper summarizes some recent results of the effect of diet restriction upon body temperature and membrane microviscosity of lymphocytes, hepatocytes and cerebellar cells of diet-restricted female Wistar rats. The treated animals were fed on an every-other-day schedule starting from the age of 3.5 months. It is suggested that a decrease in average body temperature (-1 degree C) of diet-restricted animals as compared to the ad libitum fed ones may stimulate the cells to synthesize more fluid membranes. Together with these the maintenance of the activity of protective enzymes is another key event which helps to prevent the age-dependent deterioration of cell membrane functions.

Journal Article↗

PubMedDate not supplied

Parameters to monitor aging with a possible perspective for intervention - an immunological approach.

Reliable aging markers are very rare, which are better than the chronological age or those symptoms which have such great individual variability that their scientific value is questionable. The effect of aging on immunological behavior of human (and animal) individuals is reasonably well established. In this communication an attempt is made to find an immunological marker of aging at the level of cell surface phenomena. It was observed that ion-channel activities, having a complex regulation, loose their flexible responsiveness in lymphocyte membranes during aging. A recently discovered voltage regulation of the calcium-activated potassium channels showed a distinct change with aging of human lymphocytes. A possibility to find a better marker system in complex regulatory processes is also discussed.

Journal Article↗

PubMedDate not supplied

Food restriction in female Wistar rats, IV. Morphometric parameters of cerebellar synapses.

The effect of food restriction on morphometric parameters of cerebellar synapses has been evaluated. A decrease in the number and surface density of synapses has been observed comparing 6 and 27-28 month old rats. Food restriction prevented the loss of the number and attenuated the reduction of the surface density of synaptic contacts occurring during aging. Present data support the idea that food restriction delays the appearance of age-related modifications of synaptic structures and may explain the improvement of motoric coordination and performance found in dietary restricted old animals.

Journal Article↗

PubMedDate not supplied

Food restriction in female Wistar rats: V. Lipid peroxidation and antioxidant enzymes in the liver.

The activities of antioxidant enzymes as well as the levels of basal and enzyme induced peroxidation have been investigated in liver of female Wistar undernourished rats. Food restriction was applied starting from the age of 3.5 months by feeding the animals on every-other-day schedule (EOD). Diet restriction prevented the age-dependent increase of basal and enzyme induced lipid peroxidation in both mitochondrial and microsomal liver membrane preparations. The activities of antioxidant enzyme, i.e. superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) of liver decreased during aging in ad libitum fed rats. In the diet conditioned animals, a small increase of SOD and a complete recovery of CAT activities were observed. Present data support that food restriction improved the protection against peroxidation, and this may be in close relationship with the life prolonging effect of such a treatment.

Journal Article↗

PubMedDate not supplied

Aging impairs membrane potential responsiveness as well as opening of voltage and ligand gated Na+ channels in human lymphocytes.

Depolarizing effects of increasing concentrations of extracellular K(+), as well as the repolarizing effect of bretylium tosylate (BT) were evaluated in human lymphocytes from young and elderly volunteers. Cells from elderly volunteers were less responsive to depolarization induced by increased extracellular potassium concentrations than those from young volunteers. Upon a near complete depolarization induced by 140 mM K(+) in the extracellular space, a significant amount of non-responding cells were found in samples from elderly volunteers. BT, which opens the otherwise silent Na(+) channels of partially depolarized cells, with subsequent activation of the Na(+)-K(+) pump (Pieri et al., 1989). repolarized both young and old lymphocytes. However, the degree of the repolarization was only 40% in the case of lymphocytes from elderly volunteers than from that of the young. It is suggested that an increase of membrane microviscosity, characteristic of old cells, may be at least partially responsible for the decreased responsiveness of plasma membrane functions which were observed.

Journal Article↗

PubMedDate not supplied

Food restriction in female Wistar rats. VI. Effect of reduced glutathione on the proliferative response of splenic lymphocytes from ad libitum fed and food restricted animals.

The effect of reduced glutathione (GSH) on the proliferative response of splenic lymphocytes from young, adult and old ad libitum (AL) fed as well as from old food-restricted rats was investigated. Food restriction was applied on an every-other-day schedule (EOD) starting from the age of 3.5 months. As was expected, the cells from EOD fed animals responded to concanavalin A (Con A) much better than those from age-matched ad libitum fed rats. The presence of the antioxidant GSH in the culture medium increased the response of lymphocytes in all the models taken into account; furthermore, it decreased the differences due to aging and application of food restriction. According to present knowledge, mitogenic stimulation induces free radical production, and GSH has, among others, a strong antioxidant activity. Thus, present data suggest that splenocytes from EOD animals tolerated the peroxidative stress resulting from mitogenic stimulation better than those from AL fed ones.

Journal Article↗

PubMedDate not supplied

Reduced glutathione recovers the impairment of the proliferative response of splenic lymphocytes from vitamin E-deficient rats.

The effect of reduced glutathione (GSH) on the Con A induce proliferative response of splenic lymphocytes from rats fed a normal or vitamin E-deficient diet has been investigated. The animals were killed when they were 12 months old and after 11 months of dietary treatment. As was expected, a decreased response, measured in terms of blast transformation or [(3)H]thymidine incorporation, was observed in vitamin E-deficient animals when compared with the control group. This pattern can be accounted for by the large number of dead cells found in deficient animals. GSH addition into the culture medium resulted in a strong increase of the response in both groups and it eliminated the difference caused by the different dietary regimens. Taking into account that, during proliferation, an increase of respiration occurs which increases the risk of free radical production, present data suggest that GSH may substitute vitamin E in protecting the cells.

Journal Article↗

PubMedDate not supplied

Effect of reduced glutathione on mitochondrial parameters of proliferating splenocytes from young and old rats.

The time-dependent changes of mitochondrial membrane potential and mass have been investigated on splenocytes from young, adult and old rats stimulated with Con A in the presence and absence of reduced glutathione (GSH). In addition, the basal level as well as the level of GSH during a 3-day culture period has been determined. No age-dependent changes of cellular GSH content were observed in freshly prepared splenocytes; however, in proliferating cells from old animals the expected increase in GSH levels was delayed. As regards the mitochondrial parameters, their membrane potential and mass were measured by means of the fluorescent probes rhodamine-123 (Rh-123) and nonyl acridine orange (NAO), respectively, and flow cytometry. During aging and with time of culture, an increased number of cells showed depolarization and loss of mitochondrial mass. This age-dependent impairment was completely prevented by addition of GSH to the culture medium, which resulted in a sharp increase in intracellular GSH. The present findings support the view that an impairment of the antioxidant defense system may be responsible for the damage observed in the mitochondria of proliferating splenocytes from old animals.

Journal Article↗

PubMedDate not supplied

Melatonin is an efficient antioxidant.

We have compared the peroxyl radical scavenger ability of melatonin with that of vitamin E, ascorbic acid (As.A.), reduced glutathione (GSH) and mannitol. All the antioxidants, except mannitol, prevented the lysis of human erythrocytes exposed to an azo-initiator of peroxyl radicals (2,2'-azo-bis(2-amidinopropane)dihydrochloride) at 37 degrees C. The percentage of this inhibition of erythrocyte lysis varied with the concentration of antioxidants, but the efficiency was melatonin > vitamin E > As.A. > GSH. Based on the assumption that each molecule of vitamin E scavenges two peroxyl radicals, the scavenging capacity of melatonin was four peroxyl radicals/molecule.

Journal Article↗

PubMedDate not supplied

Food restriction in female Wistar rats. VII. Mitochondrial parameters in resting and proliferating splenic lymphocytes.

The effect of food restriction on the mitochondria of resting and proliferating rat splenocytes was examined, measuring the membrane potential and mass of these organelles, by means of the specific fluorescent probes Rhodamine-123 and Nonyl Acridine Orange, respectively. Food restriction was applied on an every-other-day schedule (EOD) starting at the age of 3.5 months. The ad libitum fed (AL) animals were killed when they were 4, 11 and 24 months old, whereas the EOD rats were killed at 11 and 26 months. Resting lymphocytes from AL rats showed an age-dependent increase of both membrane potential and mass of their mitochondria. However, the mitochondrial mass increased to a larger extent when compared with the membrane potential resulting in a decrease of the respiratory quotient (RQ), i.e. of the respiratory activity per unit of mitochondrial mass. In EOD animals, the mitochondrial membrane potential was lower and the mitochondrial mass was higher in the corresponding age-matched controls, resulting in a further decrease of RQ. Following mitogenic stimulation, most of the cells from young and adult AL rat showed an increase of membrane potential and mass of their mitochondria. In contrast about 50% of cells from old AL rats had depolarized organelles after 72 h from the stimulation. Food restriction was able to prevent these alterations allowing the majority of cells, including those from old animals, to maintain the hyperpolarization of their mitochondria during the 3-day culture. In light of the well known sensitivity of mitochondrial membrane potential to peroxidative stress, present data suggest that the increase of respiration occurring during mitogenesis may increase free radical production, which is better tolerated by cells from EOD animals than by those from AL animals.

Journal Article↗