Wavelet transform: A better approach for the evaluation of instantaneous changes in heart rate variability.

The aim of our study was to validate the Vaidyanathan wavelet tool for HRV analysis during orthostatic testing. Two groups of normotensive male subjects were studied: 13 adolescents and 27 young adults. Both groups consisted of subjects with negative, (N-), and with positive family history for hypertension, (N+).

Effect of lesions to the supramammillary area of the posterior hypothalamus on atrial natriuretic peptide release following acute blood volume expansion in conscious Wistar rats.

Acute blood volume expansion (AVE) is a potent stimulus for atrial natriuretic peptide (ANP) release. Since several central nervous structures are well known for their involvement in the regulation of fluid and electrolyte homeostasis and in the secretion of central ANP, we carried our experiments on 33 conscious Wistar rats in order to determine if the integrity of the supramammillary (SMA) hypothalamic area is essential for the peripheral ANP response to AVE. We performed stereotaxic electrolytic lesions of SMA in part of the animals.

Effect of dopamine receptor blockade on the renal excretory response to acute volume expansion (AVE) in conscious Brattleboro rats.

Unlabelled: All the studies were performed on chronically cannulated, conscious Brattleboro rats, housed in metabolic cages under standard conditions. The renal excretory indices: diuresis (V), sodium (UNa.V), potassium (UK.

Renal excretory function, atrial natriuretic peptide (ANP) and plasma renin activity (PRA) during long-term sodium loading in rats.

The effect of chronic sodium loading on the level of plasma atrial natriuretic peptide (ANP) and on plasma renin activity (PRA), as well as on the renal excretory function was studied. Fifty-six standardly bred Long Evans rats were divided into three experimental groups: controls, rats drinking 170 mmol NaCl/l solution instead of water, and rats consuming food with high sodium content (850 mmol NaCl/kg) for 21 days. During the study, we measured the amount of fluid intake, the parameters of the renal function: diuresis (VU); sodium, potassium and cloride excretion (UNa V, UKV and UClV), and the dynamics of body mass.

Potentiation of the diuretic and natriuretic effect of furosemide by the calcium antagonist nifedipine.

The renal excretory function was studied in rats under control conditions, after treatment with nifedipine, with furosemide and combined treatment with nifedipine and furosemide. The experimental animals were investigated in metabolic cages. Spontaneously excreted urine was collected for 6 h (under control conditions and when nifedipine was applied) and for two hours in the experiments with furosemide treatment.

Renin-angiotensin system and renal excretory function under conditions of hypovolemia and limited sodium intake.

The renal excretory function of rats was investigated under conditions of reduced extracellular fluid volume (ECV) obtained by peritoneal dialysis with isotonic glucose solution 10% of the body mass and using sodium-deficient diet (consisting of boiled rice) with intact renin-angiotensin system (RAS) and after angiotensin converting enzyme blockade by Captopril. The experiments were made on male Wistar rats placed in metabolic cages. The diuresis, the excretion of sodium, potassium, chlorine and osmotically active substances in spontaneously released urine were tested over a period of 6 hours.

Effect of furosemide upon extracellular fluid volume depletion and kidney denervation in rats.

The effect of the diuretic Furosemide (4 mg/kg) is tested on rats housed in metabolic, cages. The excretory function of the kidneys is studied over a 2-hour period after Furosemide administration, according to the following parameters: diuresis, glomerular filtration, excretion and excretory functions of sodium, potassium, chlorine and total osmotically active substances. Reduction of the volume of the extracellular fluid (ECF) is induced by intraperitoneal administration of 0.

Method and programme for compartment analysis of exogenously introduced indicator substance.

The concept of the compartment structure of body fluids gives possibilities for finding the values of physiological characteristics such as volume of distribution, transport rate, kidney and intercompartment clearance. Their determination is made indirectly and it is based on the solution of a system of differential equations describing the behaviour of an open two-compartment system when an indicator substance is introduced. The determination of the coefficients of the equations involves a number of difficulties leading to inaccurate results due to the use of graphic-analytical methods.