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Biomedical subjects

J Hanácek

Publications and source records attributed to J Hanácek.

At least 19 recordsLinked to original sources
PubMed2002

Effects of hyperoxia and allergic airway inflammation on cough reflex intensity in guinea pigs.

Toxic influence of high oxygen concentration on pulmonary function and structures has been known for many years. However, the influence of high oxygen concentration breathing on defensive respiratory reflexes is still not clear. In our previous experiments, we found an inhibitory effect of 100 % oxygen breathing on cough reflex intensity in healthy guinea pigs. The present study was designed to detect the effects of hyperoxia on cough reflex in guinea pigs with allergic airway inflammation. In the first phase of our experiment, the animals were sensitized with ovalbumin. Thirty-two sensitized animals were used in two separate experiments according to oxygen concentration breathing: 100 % or 50 % oxygen for 60 h continuously. In each experiment, one group of animals was exposed to hyperoxia, another to ambient air. The cough reflex was induced both by aerosol of citric acid before sensitization, then in sensitized animals at 24 h and 60 h of exposition to oxygen/air in awake animals, and by mechanical stimulation of airway mucosa in anesthetized animals just after the end of the experiment. In contrast to 50 % oxygen, 100 % oxygen breathing leads to significant decrease in chemically induced cough in guinea pigs with allergic inflammation. No significant changes were present in cough induced by mechanical stimulation of airways.

Animals↗
PubMed2001

[Respiratory disorders during sleep in patients with diabetes mellitus].

Respiratory disorders during sleep are a serious medical, economic and social problem. In the submitted review the authors discuss the possible relationship between sleep disorders and diabetes. In the introduction they make the reader familiar with basic information on sleep apnoea, incl. the definition, classification and basic pathomechanisms leading to this disorder. In the subsequent part the authors discuss possible relations between the two diseases, the possible participation of diabetic autonomous neuropathy in the pathogenesis of sleep apnoea, the possible influence of hypoglycaemia on sleep quality and the possible influence of sleep apnoea on the development or deterioration of insulin resistance. The objective of the paper is to provide the professional public, but in particular diabetologists, with an overall review of the problem based on most recent data from the literature and to draw attention to the fact that respiratory sleep disorders in diabetics are relatively frequent and that to this problem attention must be paid in practice and in medical research.

Autonomic Nervous System Diseases↗
PubMed1996

[Functional and morphological changes in the respiratory organs of cats after long-term exposure to pure normobaric oxygen].

BACKGROUND: Pulmonary oxygen toxicity is very well known and proved. The influence of hyperoxia on the respiratory reflexes is not known till now. MAIN PURPOSE: To ascertain if long-lasting breathing of pure normobaric oxygen (PNO) alter respiratory reflexes. METHODS: 34 adult cats of both sexes, weighing 2.5-4.0 kg, were used in two experiments. In the first experiment 16 animals with inserted chronic tracheal cannula (CTC) were used. In the second experiment 18 animals without CTC were employed. Part of animals in both experiments was exposed to PNO (day by day for 2 weeks, 10 h daily), remaining animals were exposed to room air under the same conditions. Side tracheal pressure was recorded in unanesthetized animals of the first experiment. The second experiment was performed in anaesthetised animals (Pentobarbital Spofa, 35 mg/kg, i.p.). Oesophageal pressure and blood pressure in femoral artery were recorded. Cough reflex, sneezing and aspiration reflexes were induced by mechanical stimulation of airway mucosa. Pulmonary chemoreflex was elicited by i.v. administration of 50 micrograms phenyl biguanid. Hering-Breuer inflation reflex was induced by lung inflation with pressure of 1 kPa. Reactivity of tracheal and pulmonary smooth muscle to histamine were measured in vitro. Differences in recorded parameters between animals exposed to PNO, and to room air, were tested by Mann-Whitney-Wilcoxon test and by Student's t-test. When p < 0.05, the differences were recognized as significant. RESULTS: Significant decreasing of the expiratory parameters of the cough induced from laryngopharyngeal mucosa, inhibition of sneezing, and inhibition of aspiration reflex, were found in animals exposed to PNO. Relaxing reaction of tracheal smooth muscle of control animals to histamine was reversed to contraction in animals exposed to PNO. Morphological changes of the respiratory tract induced by influence of oxygen were found CONCLUSION: Long-lasting breathing of PNO induced changes of respiratory reactions elicited mainly from upper airway.(Fig. 6, Tab. 3, Ref. 22)

Animals↗
PubMed1996

Effects of irritants on airways reactivity.

The authors observed reactivity changes of airways smooth muscles after exposure of experimental animals to toluene and hyperoxia. The pretreatment with antioxidants did not prevent these changes.

Animals↗
PubMed1989

Effects of atropine, acetylsalicylic acid, FPL 55712, and phentolamine on increased histamine responsiveness of cat lung strips under conditions of airway inflammation.

Our recent in vitro studies on airway smooth muscles of cats with turpentine oil inflammation showed an increase of isometric tension of the lung strips to histamine application. This communication describes the effect of atropine, acetylsalicylic acid, FPL 55712, and phentolamine on the histamine contractions of the lung strips derived from control and experimental groups of cats. Pretreatment of the lung strips with atropine and acetylsalicylic acid had no significant effect on histamine induced contraction. FPL 55712 significantly decreased the mean values of isometric contractions after the low doses of histamine in experimental groups of strips. The isometric contractions after higher doses of histamine were not affected by FPL 55712 in both groups of strips. The significant increase of histamine contractions of the lung strips induced by experimental inflammation was reduced by phentolamine. The role of alpha adrenergic receptors in the increased responsiveness of the inflamed lung tissues to histamine is discussed.

Animals↗
PubMed1987

Influence of experimentally induced airway inflammation on the reactivity of cat lung parenchymal strips to histamine and acetylcholine.

The reactivity of cat lung parenchymal strips to histamine and acetylcholine in vitro was studied at various stages of inflammation of the airways induced experimentally by the intratracheal administration of turpentine oil or Staphylococcus aureus, both in aerosol form. With histamine, the contractile responses of the lung strips were enhanced depending on the stage of turpentine oil inflammation. Similarly, the lung strips responded more to histamine in the staphylococcal inflammation. The reactivity of the lung strips to acetylcholine remained mainly unaffected by either type of inflammation.

Acetylcholine↗
PubMed1987

Influence of sulphur dioxide breathing on defensive reflexes of the airways.

The influence of sulphur dioxide (SO2) on cough and expiratory reflexes was studied in 22 anaesthetized (pentobarbital, 30 mg/kg i.v.) rabbits. The cough reflex (CR) was elicited by tracheobronchial mucous membrane stimulation, using a soft venous catheter. In order to induce the expiratory reflex (ER) irritation of the larynx was performed by a silon fibre loop. The strength of both reflexes was assessed from the interpleural pressure fluctuation before SO2 breathing, immediately after, and 30-120 minutes after SO2 breathing had been stopped. The animals breathed SO2 in 200-300 ppm concentration through a tracheal cannula. The influence of SO2 on the direct dependence of lung inflation pressure magnitude (LIPM) on strength of the expiratory reflex (ERS) was tested. It was found that elicitability and strength of the cough reflex decreased immediately after SO2 breathing had been stopped, and did not reach the preexposure level at the end of the experiment, i.e. 2 hours after discontinuation of SO2 breathing. The direct dependence of LIPM on ERS in unaffected rabbits [10] was abolished immediately after SO2 breathing had been stopped but was present again 30-60 minutes later, and did not differ significantly from the control values. The results give evidence of the strong depressive influence of SO2 on the defensive reflexes of the airways in rabbits.

Animals↗
PubMed1985

Reactivity of cat tracheal smooth muscle to histamine under conditions of experimentally induced inflammation.

The reactivity of cat tracheal smooth muscle to histamine in vitro was studied at various degrees of inflammation of the airways induced experimentally by the intratracheal administration of turpentine oil or Staphylococcus aureus, both in aerosol form. Tracheal smooth muscle preparations from the control animals did not respond to histamine in doses of 10(-9)-10(-3) mol X 1(-1). In tracheal preparations from three groups of cats with turpentine oil inflammation induced 24 h, 48 h and 15 days previously, histamine caused contractions in 20, 70 and 24% of the cats, respectively, according to the degree of inflammation. All tracheal preparations from cats with staphylococcal inflammation responded to histamine by contraction. Atropine, acetylosalicylic acid and phentolamine did not abolish histamine contractions in tracheal preparations, but clemastine did.

Animals↗
PubMed1984

Influence of lung stretch receptors on the cough reflex in rabbits.

The cough reflex in anaesthetized rabbits was elicited by irritation of the larynx with ammonia, inhalation of ammonia into the lungs, and mechanical stimulation of the tracheobronchial tree with a catheter. After block of lung stretch receptors with sulphur dioxide and virtual abolition of the Breuer-Hering inflation reflex, the cough response to all three stimuli was far less frequent and, when it occurred, was weaker especially with respect to the expiratory efforts. It is concluded that the Breuer-Hering reflex enhances the cough reflex, although modification of the sensitivity of tracheobronchial cough and irritant receptors by sulphur dioxide may also influence the cough.

Animals↗
PubMed1982

Modification of the intensity of the expiration reflex during short-term inflation of the lungs in rabbits.

Too little is known of the mechanisms participating in the regulation of defence reflexes of the organs of respiration. The activity of respiratory tract--in particular lung stretch and cough receptors--may play an important role. In the present study the authors investigated the effect of short-term inflation of the lungs, during which lung stretch receptors are mainly stimulated, on the expiration reflex, which is one of the respiratory defence reflexes. The experiments were carried out on 18 rabbits (2.5-2.8 kg) under general anaesthesia (Pentobarbital Spofa, 30 mg.kg-1 i.v.). The VT, V', Ppl and systemic BP were recorded. The expiration reflex was elicited by stimulating the vocal folds with a silon fibre loop during resting respiration and during inflation of the lungs with pressures of 0.49, 0.98 and 1.47 kPa. The criterion of the intensity of the expiration reflex was the Ppl expressed in kPa. The authors found that the intensity of the expiration reflex during resting respiration was 0.29 +/- 0.02 kPa (S.E.M.). An inflation pressure of 0.49 kPa raised it to 0.69 +/- 0.06 kPa, a pressure of 0.98 kPa raised it still further to 1.12 +/- 0.06 kPa and a pressure of 1.47 kPa raised it yet again to 1.59 +/- 0.08 kPa. In the authors' opinion, the increase in the intensity of the reflex is due to augmented activity of lung stretch receptors.

Animals↗
PubMed1979

Cough reflex changes in local tracheitis.

The authors describe changes in the cough reflex in unanaesthetized cats with experimental local tracheitis. Inflammation was produced by a silk suture fixed in the trachea and cough was elicited by mechanical stimulation of different parts of the respiratory tract mucosa. The resultant cough values (the number of efforts, the intensity of the maximum effort and the intensity of the attack) were compared with the corresponding values in healthy cats. In animals with a tracheal suture, inflammation was confined to the trachea. The intensity of cough elicited by stimulation of this region increased significantly compared with normal (on the 15th to 17th day of inflammation), whereas cough elicited from the laryngopharyngeal and tracheobronchial region did not. On about the 20th day of inflammation the authors found a decrease in the intensity of the maximum effort of cough elicited from the inflamed part of the trachea and a decrease in the intensity of the maximum effort and the intensity of the coughing attack elicited from the laryngopharyngeal and tracheobronchial region. They assume that the decrease could have been due to the development of protective inhibition in central structures participating in integration of the cough reflex.

Animals↗