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Biomedical subjects

F Palecek

Publications and source records attributed to F Palecek.

At least 55 records · Page 3Linked to original sources
PubMed1976

Pattern of breathing in the rat.

The basic ventilation values - tidal volume (VT), breathing frequency (f), minute ventilation (VE) and the duration of inspiration (TI) and expiration (TE) -- were determined in adult male rats. The range of these values is given and the pattern of breathing is defined as the relationship between VE and VT, which in the rat is linear throughout its entire range. The role of TI and TE in changing f in the rat were evaluated. The breathing pattern of the rat was compared with data for the rabbit and man, using percentual expression of the basic values. A shift of the breathing pattern to higher f values was observed in rats with experimental lung diseases. In these rats, the inhalation of 100% O2 shifted the pattern of breathing markedly to lower VE values, though not to values comparable with the controls. Bilateral cervical vagotomy was followed by a pronouced decrease in f, an increase in VT and T1 persisted even after vagotomy, however; it can be assumed that this relationship is effected either by means of receptors in the chest muscles, or by the direct action of CO2 which is used to stimulate breathing, on the bulbopontine pacemaker.

Anesthesia↗
PubMed1976

Causes of experimental pulmonary hypertension in rats.

Experimental pulmonary hypertension was induced in young male rats by means of tracheoconstriction and repeated injections of aqueous bean (Phaseolus vulg.) extract into the trachea. After 120 days, the blood pressure of the experimental and control animals was measured in the pulmonary artery with a shaped polyethylene catheter, without opening the chest. In all the experimental animals the blood pressure in the pulmonary artery was higher than in the controls. The mean pressure in the pulmonary artery of the experimental rats was 25 +/- 1 torr and in the controls 16 +/- 0.4 torr. The right ventricle of the experimental animals was larger than in the controls. No difference was found between the systemic blood pressure values, measured in the femoral artery, in the experimental animals and the controls. The experimental animals had a faster heart rate. Cardiac output, measured by the dye dilution method, was the same in the control and experimental animals and there was likewise no difference in the PO2 PCO2 and pH values in the arterial blood. The inhalation of oxygen instead of air did not affect the blood pressure in the pulmonary artery. The pulmonary blood vessels were evaluated quantitatively in histological sections of the experimental and control animal's lungs. There was no different between the thickness of the media of the distal pulmonary vessels, expressed as a percentage of the outer diameter of the vessel, in the experimental animals and the controls. A media thicker than 7% was found in 15% of the evaluated vessels from experimental animals and in 8% of those from the controls. No correlation between the mean thickness of the media and the mean blood pressure in the pulmonary artery was found in any of the animals.

Animals↗
PubMed1975

Inflation reflex in the rat.

The Breuer-Hering inflation reflex [BHIR] was elicited in conscious and anaesthetized rats by inflating the lungs with constant pressures of 5--20 cm H2O. The reflex was elicited well in conscious animals, but even with the maximum stimulus [inflation of 20 cm H2O, corresponding to about 4.5-fold the tidal volume] the duration of apnoea did not exceed 4 control respiration cycles. In anaesthetized animals, the same stimulus let to apnoea lasting 180--400 control respiration cycles on the average, according to the type and depth of general anaesthesia. The duration of apnoea in occlusion of the air passages in the expiratory position increased with the depth of anaesthesia, while in occlusion of the air passages at the peak of inspiration it was shortened. Stimulation of chemoreceptors [inhalation of a mixture 4% CO2 in O2 or of 8% O2 in N2] did not influence the elicitability or duration of the BHIR, nor did cooling the rats to 28 degrees C or heating them to 38 degrees C. The mean respiration frequency was 98 c/min in unanaesthetized rats, 96 c/min in urethane anaesthesis and 79--48 c/min in halothane anaesthesia, according to the depth of anaesthesia. Bilateral cervical vagotomy reduced mean respiration frequency to 35.6 c/min in conscious rats and to 31 c/min in urethane-anaesthetized animals. The results indicate the existence of species-related differences between basic regulatory mechanisms in the rat and certain other mammals.

Animals↗
PubMed1975

Participation of the Breuer-Hering inflation reflex in regulation of respiration frequency in anaesthetized rats.

The respiration frequency and Breuer-Hering inflation reflex (BHIR) values were compared in anaesthetized rats after unilateral vagotomy. Nos significant differences were found in the decrease in respiration frequency after transection of the right of left vagus and there were no differences in BHIR values in correlation to conduction by the right or left vagus. With unilateral vagotomy and an inflation pressure of 20 cm H20 the BHIR values fell to about one fourth of the control values. Progressive cooling of the contralateral vagus led at 8-10 degrees C to a non-significant decrease in respiration frequency to 87% of the initial value; in this state the BHIR could not be elicited. Further cooling of the vagus to 0 degrees C reduced respiration frequency to the same values as in bilateral vagotomy. The discrepancy between the mild decrease in respiration frequency and simultaneous disappearance of the BHIR shows that changes in respiration frequency in anaesthetized rats are not directly correlated to the presence of the BHIR.

Anesthesia↗
PubMed1975

Carrageenin-induced experimental pneumonia in rats.

The authors verified the possibility of modelling pneumonia by the intratracheal administration of carrageenin solution into the lungs of rats. The most satisfactory dose was found to be 0.5 ml 0.7% carrageenin solution administered at 40 degrees C. The disease, evaluated by the morphological and functional signs, culminated after two days. Both macroscopically and histologically the lungs displayed typical signs of catarrhal suppurative aspiration bronchopneumonia. Functionally, marked tachypnoea (mean 180 cycles/min as against 110 c/min in the conscious controls) and raised functional residual capacity were found. A drop in the respiration rate and in FRC after bilateral cervical vagotomy indicated that a reflex component participates in the origin of the above two signs.

Airway Resistance↗
PubMed1975

Lung function in acute paraquat intoxication.

Functional and morphological examination of the lungs was performed in rats 48 hours after intratracheal injection of 0.5 mg/kg of the herbicide paraquat. Pronounced tachypnoea was observed (235+/-20 c/min), which also persisted under urethane anaesthesia (210+/-18 c/min). In control rats the mean breathing rate was 115+/-11 and 90+/-9 c/min in wake and anaesthetized rats respectively. The rate of breathing decreased to comparable values in experimental and control rats after bilateral cervical vagotomy. The functional residual lung capacity was significantly increased in experimental rats. After vagotomy also this increase of functional residual capacity became normalized. Histologically the disease was characterized by focal formation of hyaline membranes and oedema with occasional haemorrhages and signs of inflammation. The significant role fo vagal function in lung pathology is demonstrated.

Animals↗