[A compartment analysis of the significance of extracellular fluid volume for body fluid dynamics].

The curve of a reduction in plasma concentration of the indicator substance creatinine for a period of 120 to 240 min was investigated after single intravenous administration of creatinine in a dose of 150 mg/kg on dogs. A model for two compartment distribution of the indicator substance was used as the first compartment was intravasal, but the second--interstitial space of body fluids. The following parameters were estimated: renal clearance, volume of distribution, glomerular filtration, intercompartment clearance and velocity constants of transport between the two compartments.

A program package for self-assessment and examination in biochemistry.

A BASIC program has been developed for self-evaluation and testing of an individual's knowledge of main categories in biochemistry. The computer tests permit sequential or random distribution of items, random distribution of answers in each item at each new run, effective feedback control with the student, use of a program clock to determine different time allowance, precise and quick analysis and grading of student's answer thus saving the time and labour of examiners. Editing, deleting and appending of new items is easily achieved.

Effect of bevelling on C1-selective microelectrodes: experimental and model study.

Bevelling of the ultra-fine tips of C1-selective microelectrodes (ME) based on liquid ion-exchanger Corning 477913 caused significant decrease in ME resistivity, increase in sensitivity dependent on its initial value and decrease in selectivity constant for bicarbonates (KC1,HCO3) from 10:1 to approximately 8:1. Bevelling did not affect KC1,NO3 which had value below 1 due to higher selectivity of the ion-exchanger for nitrates. The observed experimental alterations in ME behavior after bevelling were in agreement with those predicted by a relatively simple electrical model comprising of two conductive pathways in parallel having opposite in sign sensitivities.

Suprachiasmatic nuclei lesions do not eliminate the circadian rhythms of electrolyte excretion in the rat.

The 24-hour variations in 2-hour diuretic and saluretic action of furosemide (4 mg/kg) given at 8, 12, 16, 20, 24 or 4 hr and the circadian rhythms of food and water intake, urine and electrolyte excretion followed for two consecutive days at 4-hour intervals were investigated in suprachiasmatic nuclei (SCN)-lesioned or sham-operated male Wistar rats. The results showed that: a distinct 24-hour rhythm in furosemide-induced urine, sodium and chloride excretion persisted after SCN lesions, and the lesions abolished the circadian rhythms of food and water intake but only desynchronized the individual 24-hour variations in electrolyte excretion. We concluded that SCN play a role as a central synchronizer but not as a major oscillator of the circadian rhythms of electrolyte excretion in the rat.