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J Prazma

Publications and source records attributed to J Prazma.

79 records · Page 5Linked to original sources
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Cochlea and heart as end-organs in small vessel disease.

Many studies have been done recently to determine the role of various stresses on the heart and peripheral vasculature. Although damage to coronary arteries and renal vessels has been well described, the ear as an end-organ in small vessel disease has been largely neglected. In a previous study, we examined the effects of noise, hypertension, and an atherogenic diet on the microvasculature of the cochleas in rats. The present study examines the effects of these stresses on the hearts of the same rats. The technique used to examine microvascular blood flow was the injection of unlabeled microspheres prior to killing. We found that the blood flow in the cochleas was reduced significantly in hypertensive animals exposed to noise or an atherogenic diet compared to that of normotensive or hypertensive control animals. The hearts of such animals, however, showed decreased myocardial blood flow only when compared to those of normotensive control animals, not when compared to those of hypertensive control animals.

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The role of nitric oxide in the neural control of nasal fluid production.

The production of nasal fluids serves an important role in the protection of the upper respiratory system, but can also be a troublesome symptom of rhinitis. The chief sources of nasal fluids are serous and mucous glandular secretion, epithelial goblet cell exocytosis, and exudation from submucosal blood vessels. This study was designed to investigate the role of nitric oxide in neurogenically mediated nasal vascular exudation and mucus secretion. A rat model of the naso-nasal reflex was developed in which one nasal cavity was challenged with histamine while albumin and mucin production were measured in the continuously perfused contralateral side. Histamine challenge was associated with a significant rise in contralateral albumin and mucin content. Perfusion with a nitric oxide synthase inhibitor (L-NAME) in the nasal cavity contralateral to nasal challenge was found to block albumin leakage, but not mucin secretion, on that side. The inhibition of vascular exudation was overcome by the addition of L-arginine, the natural substrate of nitric oxide synthase, to the perfusate. Treatment of the ipsilateral nasal of the ipsilateral nasal cavity with L-NAME did not significantly after the contralateral response. A high correlation was observed between albumin and mucin concentration in the perfusate. These findings indicate that NO is a mediator of the effector arm of the naso-nasal reflex that increases vascular permeability, but is not involved in the sensory nerve afferent pathway or in reflex mucin release. Further elucidation of the role of NO in nasal physiology may lead to novel pharmacotherapeutic approaches to the treatment of allergic and non-allergic rhinitis.

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Effect of glycerol on cochlea microcirculation.

Microcirculation in the cochlea of l2 normal anesthetized guinea pigs was investigated after intravenous infusion of 2.4 ml/kg of 40% glycerol. In these experiments endolymphatic PO2, blood pressure, cochlear microphonics, and endocochlear potentials were recorded. Administration of glycerol caused a significant increase in endocochlear PO2 for about 30 minutes. The improvement of hearing in patients with Meniere's disease is thus not only a result of the reduced hydrostatic pressure, as has been demonstrated by others, but may also be the result of vasodilatation, which improves microcirculation in the cochlea with resultant increases in endocochlear PO2.

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