Respiratory effects of intravenous lobeline in normal subjects and in patients with mitral stenosis.

Patients with mitral stenosis are known to have a diminished ventilatory response to inhalation of carbon dioxide, as compared with normal subjects. Reduced responsiveness of the respiratory centre (Pauli, Noe, and Coates, 1960) and/or altered mechnical properties of the lungs are assumed to be responsible for this change (Bruderman, Braun, and Rogel, 1965). The ventilatory response to CO2 inhalation is mediated partly through peripheral chemoreceptors (Heymans, Bouckaert, and Dautrebande, 1930), and the possibility of decreased activity of these receptors in the presence of mitral stenosis has not been investigated. In the present study, designed to determine the role of the peripheral chemoreceptors in healthy subjects and in patients with mitral stenosis, hyperventilation was produced by intravenous administration of small doses of lobeline. This drug in small doses stimulates only the peripheral chemoreceptors, and not the respiratory centre (Liljestrand, 1951). As reports of the effect of lobeline on bronchial smooth muscle tone have been contradictory (Dautrebande et al., 1948; Daly and Schweitzer, 1951; Nadel and Widdicombe, 1962, 1963), its effect on the pulmonary mechanics in normal subjects and in patients with mitral stenosis was also investigated.