We will continue our study on the separate reflex influences of different types of airways receptors using several experimental approaches: differences in location along the airways circumference of slowly adapting stretch receptors and "irritant" receptors, their different susceptibility to local anesthetics and the selective block of stretch receptors by sulphur dioxide. This project is very likely to be completed, in most of its aspects, within the coming year. We will start a study of the accessibility of airways receptors of known location along the tracheo-bronchial tree either through the pulmonary or the bronchial circulation. This study will verify the widely accepted criterion of establishing either a peripheral or proximal location for airways receptors on the basis of their accessibility to substances injected either into the pulmonary or systemic circulation. Furthermore, it could provide data on the anastomoses and possible diffusion between the pulmonary and bronchial vascular beds.