Sex-related and age-related differences in platelet function in vitro: influence of hematocrit.

Even minor changes in the sodium citrate concentration of citrated plasma from young probands due to diverse hematocrit values were found to affect platelet functional activity following in vitro stimulation. There were no differences between men and women in the platelet aggregation and TXB2 production of young probands with similar hematocrit values. Platelets from elderly persons virtually failed to respond to such changes in plasma sodium citrate. Mechanisms of increased platelet activity in the elderly are discussed. It is assumed that the age-related differences are caused by a more pronounced platelet response even to lower plasma calcium levels in citrated plasma.

[The effect of calcium antagonists on total calcium and magnesium levels in the aorta of rabbits after administration of dietary cholesterol]. / Vplyv kalciových antagonistov na celkový obsah vápnika a horcíka v aorte králikov po podávaní cholesterolovej diéty.

The objective of the work was to investigate the effect of calcium blockers--dilthiazem (2 mg.kg-1.day-1), isradipine (2.5 mg.kg-1.day-1) and verapamil (0.25 mg.kg-1.day-1) on the calcium and magnesium content of the rabbit aorta with experimental atherosclerosis induced by a 1% cholesterol diet. In the aorta of rabbits kept on a cholesterol diet the calcium and magnesium content, as compared with a control group on a ordinary diet, increased significantly. In the experimental groups to whom during the eight-week period on the cholesterol diet at regular 12-hour intervals calcium antagonists were administered the calcium and magnesium content of the aorta reached normal levels. The antiatherogenic effect was, however, produced only by verapamil when administered in therapeutic doses.

Impaired tubular reabsorption of magnesium after renal transplantation.

Tubular reabsorption of magnesium ( TRMg ) was calculated from the values of plasma ultrafiltrable Mg and urinary Mg in 36 patients with transplanted kidneys. The study revealed a defect in TRMg in all investigated patients. The lowest TRMg values were found in patients with poor function of the transplanted kidneys. TRMg increased in relationship with the increment in glomerular filtration rate, nevertheless in the majority of the cases the TRMg values did not reach the values of healthy individuals.

Impaired renal tubular reabsorption of magnesium (TRMg) in Ca-containing kidney stone formers.

Calculations of TRMg% were performed in 69 kidney stone formers. In patients with impaired TRMg significant increment in urinary Ca excretion and urinary Ca/Mg ratio was found. A life-long Mg supplementation is suggested in order to prevent Mg deficiency, stone recurrency and renal insufficiency.

Chronic renal insufficiency (CRI) in urolithiasis.

In 80 adult kidney stone formers (52 with reversible and 28 with irreversible renal impairment) laboratory and clinical data were evaluated to estimate the share of abnormalities in the metabolism of stone forming substances in the development of renal impairment, and to search for the causes of the irreversibility of renal impairment. The study confirmed the previous results from this laboratory suggesting a causal relationship between renal impairment and metabolic disorders. No significant differences in the incidence of metabolic disorders or in therapy have been found in patients with irreversible renal impairment as compared to those with progressive deterioration of renal function. Irreversible renal impairment developed in relationship with bilateral kidney stone formation and recurrent urinary infection.