ARTICOLI ORIGINALI   

Minerva Pneumologica 2014 March;53(1):35-42

Copyright © 2014 EDIZIONI MINERVA MEDICA

lingua: Inglese

Effects of endothelin on respiratory system hysteresis and mechanics measured by the end-inflation occlusion method in the rat

Rubini A., Morra F., El-Mazloum D.

Department of Biomedical Sciences, Section Physiology, University of Padua, Padua, Italy

AIM: Aim of the present study was to investigate the effects of endothelin on respiratory system mechanics and hysteresis in the rat.
METHODS: Respiratory mechanics were measured by the end-inflation occlusion method in eight anaesthetised, positive-pressure ventilated rats before and at different times (5, 10 and 20 minutes) after intraperitoneal endothelin administration. Endothelin’s effects on respiratory system hysteresis were also measured by a previously described method.
RESULTS: Confirming previous results obtained by different methods in open chest animals, we found that endothelin affects respiratory system mechanics in almost intact animals also, increasing the “ohmic” component of airway resistance. No significant effects were instead detected on the additional visco-elastic component of resistance due to stress relaxation. At variance with previously reported results pertaining to open chest animals in which the isolated lung elastance was measured, we found decreased respiratory system elastance (including chest wall). The possible responsible mechanisms are addressed. In addition, maybe because of a stimulating effect on alveolar surfactant secretion, endothelin was demonstrated to decrease respiratory system’s hysteresis, thus reducing the inspiratory elastic work of breathing.
CONCLUSION: Endothelin showed important effects on respiratory mechanics. It is suggested that the effects we experimentally found in the rat may also occur in spontaneous human diseases characterised by increased plasmatic endothelin levels, such as hypertension, stroke, pulmonary hypertension, heart failure.