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Biomedical subjects

R Eccles

Publications and source records attributed to R Eccles.

At least 91 records · Page 5Linked to original sources
PubMed1987

Electromyographic responses of a nasal muscle to stimulation of the nasal vestibule in the cat.

1. The effects of nasal stimulation using an air jet or balloon on the electromyographic (e.m.g.) activity of a nasal muscle, the levator labii superioris alaeque nasi component of the quadratus labii superioris muscle, were studied in the anaesthetized cat. 2. Respiratory related nasal e.m.g. activity was recorded and this normally consisted of two components, one coinciding with the onset of inspiratory airflow and a larger component which commenced at the onset of expiratory airflow and often persisted until the onset of the following inspiratory airflow. 3. An air jet (room air, 1-8 l/min, temperature 24 degrees C) applied to the nasal vestibule by means of a small nozzle caused an increase in the amplitude of the ipsilateral spontaneous nasal e.m.g. activity. 4. The increase in nasal e.m.g. activity caused by the nasal air jet was unaffected by warming the airflow from 30 to 40 degrees C. 5. A sustained increase in nasal e.m.g. activity was caused by application of pressure to the walls of the nasal vestibule by means of a small balloon. 6. Section of the ethmoidal and infra-orbital branches of the trigeminal nerve abolished the increase in nasal e.m.g. amplitude caused by nasal stimulation with the air jet, whilst section of the facial nerve abolished the spontaneous respiratory nasal e.m.g. activity. 7. The results indicate that there are sensory receptors in the nasal vestibule which respond to nasal positive pressure and cause a reflex increase in nasal e.m.g. activity.

Action Potentials↗
PubMed1987

The effect of alcohol ingestion upon nasal airway resistance.

The effect of ingestion of moderate amounts of alcohol, on nasal airway resistance, was investigated in eight normal human subjects. Alcohol was found to significantly increase both inspiratory and expiratory nasal airway resistance, P less than 0.01. The implications of this finding are discussed, in terms of its relevance to the obstructive sleep apnoea syndrome.

Adolescent↗
PubMed1987

A new technique using a nasal cast for anterior rhinomanometry.

A new method of sealing a pressure sensing tube into the nostril for anterior rhinomanometry is described. This involves the use of a nasal cast made from dental impression material. The results demonstrate that the nasal cast technique gives the same resistance values as the standard nasal tape technique. Obstruction of one nostril with a nasal cast for fifteen minutes is shown to have no effect on nasal resistance. The advantages of the nasal cast method compared with the nasal tape method are described.

Adult↗
PubMed1986

Nasal vasomotor responses in man to breath holding and hyperventilation recorded by means of intranasal balloons.

Nasal vasomotor responses were recorded in conscious human subjects by means of water filled balloons. Hyperventilation caused an increase in intranasal balloon pressure associated with vasodilatation whereas breath holding caused a decrease associated with vasoconstriction. The amplitude of the nasal vasomotor response was influenced by the nasal cycle with the greatest response always observed on the congested or low airflow side of the nose. The results suggest that an elevated arterial level of carbon dioxide causes a pronounced vasoconstruction of the nasal blood vessels and that this response may be clinically relevant in controlling nasal bleeding.

Humans↗
PubMed1983

The role of sympathetic efferent activity in the regulation of brain temperature.

The role of nasal heat exchange in the control of brain temperature has been studied in cats, pigs, ducks and rabbits during acute experiments under general anaesthesia. Nasal air flow at physiological rates caused hypothalamic temperature to fall at between 0.2 and 0.5 degrees C/min in cats, pigs and ducks, which all have arterial rete systems that can cool blood flowing to the brain, but not in rabbits, which lack an arterial rete. Bilateral stimulation of cervical sympathetic trunks reduced or abolished the brain cooling effect of nasal air flow in cats, pigs and ducks. After a period of airflow during which brain cooling was reduced by sympathetic stimulation, the end of stimulation was sometimes followed by marked and rapid brain cooling, indicating re-perfusion through ischaemic cooled tissues. Cervical sympathetic stimulation caused a reduction in resistance to nasal airflow in all species studied, by inducing vasoconstriction and shrinkage of the nasal mucosa. In species with well-developed arterial retia, the effect of cervical sympathetic stimulation in regulating nasal cooling of the brain is probably mediated by controlling blood flow through the nasal mucosa. Although this vascular control also occurs in rabbits, they cannot selectively cool the brain and sympathetic stimulation has no effect on rabbit brain temperature.

Animals↗
PubMed1983

The effect of menthol on nasal resistance to air flow.

Total nasal resistance to airflow was measured in thirty-one subjects before and after five minutes' exposure to menthol vapour. Menthol inhalation had no consistent effect on nasal resistance but the majority of subjects reported an increased sensation of nasal airflow and a cooling effect of menthol. The results indicate that menthol stimulates cold receptors in the nasal mucosa to create an increased sensation of airflow. No evidence was found in support of any nasal decongestant action for menthol.

Adult↗
PubMed1983

The isolation of prostaglandin E from pig nasal mucosa.

Prostaglandins of the E series (PGE) have been shown to be potent nasal vasoconstrictors but have not previously been isolated from the nasal mucosa. Here we report the isolation of a biologically active substance with properties similar to PGE from pig nasal mucosa. The substance was identified as PGE on the following criteria: 1 our isolation procedure demonstrated the presence of a biologically active polar acidic lipid; 2 caused contractions of the isolated rat stomach fundic strip similar to PGE2; 3 caused a prolonged nasal vasoconstriction similar to PGE2; 4 travelled on thin layer chromatogram with PGE. The PGE found in the nasal mucosa may have a role in the regulation of mucosal blood flow in normal and pathological conditions.

Animals↗
PubMed1983

A method for evaluation of blood substitutes in the conscious animal.

Physiological evaluation of new and potential blood replacement agents has not kept pace with the development of such agents. Current procedures involve partial or total blood replacement in the anesthetized animal. This introduces the variable of anesthesia and eliminates the ability to observe behavior changes during blood replacement. Clinically, many patients receive blood or will receive artificial agents while sedated or under anesthesia, whereas others will be conscious. It is essential that evaluative studies be performed on the awake animal using procedures that are nontraumatic and nonrestrictive. A technique for isovolumic exchange perfusion utilizing an indwelling, heparin-coated, double-lumen catheter in the right atrium of a conscious rat is described. This animal model system permits continuous pre- and postperfusion monitoring. Nearly total blood replacement with perfluorochemical blood substitutes causes no discerniable discomfort or adverse reactions in the animal. Such animals thrive and replace missing hematologic components in 1-3 wk. The technique described can, with minimal modification, be used for isovolumic exchange perfusion of larger animals.

Animals↗
PubMed1983

Effects of prostaglandins E2, I2 and D2 on pig nasal vasculature.

The effects of the prostaglandins (PG) E2, D2 and I2 were studied on the nasal vasculature of the anaesthetized pig. PGD2 caused vasoconstriction followed by a prolonged vasodilation whereas PGI2 only caused vasodilation. The effects of PGE2 were variable with vasoconstriction in 6 out of 7 pigs and vasodilation in 1 pig.

Animals↗
PubMed1983

Sympathetic control of nasal erectile tissue.

A model is described to explain the oscillations in sympathetic tone observed in the erectile tissue of the nasal mucosa. The sympathetic innervation of the nose exhibits two types of activity, (A) oscillations in tone in phase with respiration, (B) reciprocal changes in sympathetic tone which are associated with a nasal cycle of airflow between the two nasal passages over a period of 1-4 hr. Type (A) oscillations may be caused by a loose coupling between groups of nasal vasomotor neurones and respiratory neurones. Type (B) reciprocal changes in sympathetic tone may be regulated by a "central rhythm" of nervous activity and by sensory input from the nasal mucosa.

Animals↗
PubMed1982

The central reciprocal control of nasal vasomotor oscillations.

1. Nasal vasomotor oscillations were studied in 23 anaesthetised cats. The oscillations occurred in all cats and showed both respiratory (vasoconstriction in inspiration) and non-respiratory rhythms. In all cases the oscillations were asymmetrical between the two sides of the nose, and the side with greater oscillations also had a higher level of nasal vasoconstriction. 2. Oscillations shifted from one side to the other, both spontaneously and in response to stimulation of the brain-stem reticular formation. Induced shifts were nearly always to the stimulated side, and preceded by ipsilateral vasoconstriction and contralateral vasodilation. This reciprocal pattern was shown in 19 out of 89 responsive sites, and is similar to changes shown spontaneously in the nasal cycle. 3. Non-respiratory oscillations were seen at some time in most preparations and varied from frequency doubling to complete independence from respiration. 4. The evidence presented indicated that nasal vasomotor oscillations are driven from sympathetic oscillators which may be independent of, or can be entrained by, central respiratory activity. The oscillators show reciprocal inhibition, and electrical stimulation over a poorly-defined area of the brainstem reticular formation can shift the balance of activity between them, though responses from any one site depend on the existing state of the oscillating system.

Animals↗
PubMed1981

Sympathetic innervation of the nasal mucosa of the pig.

Nasal disorders such as atrophic rhinitis in the pig are widespread and are of economic importance in livestock production. A better understanding of the basic physiology of the nasal mucosa could help in the study and treatment of nasal disorders. This paper presents a simple method which may prove useful in studies on the autonomic innervation of the nasal blood vessels. The results demonstrate the great sensitivity of the nasal blood vessels to sympathetic activity and indicate that there may be a vascular connection between the two nasal passages.

Animals↗
PubMed1981

Asymmetry in the autonomic nervous system with reference to the nasal cycle, migraine, anisocoria and Menière's syndrome.

Studies on the nasal cycle have demonstrated that the autonomic tone to the nose is asymmetrical and oscillates in a regular cycle. Autonomic tone may be regulated from a centre in the hypothalamus and normally there is a balance between he autonomic tone of the right and left halves of the body. However, under stress or with hypothalamic instability this balance may be disrupted and result in the marked autonomic asymmetry seen in migraine or Meniér's syndrome. Research on the nasal cycle in conditions where autonomic asymmetry is apparent could change the entire concept of autonomic control.

Airway Resistance↗