OBSERVATIONS ON THE PERFUSED LUNGS OF THE GUINEAPIG

¹ The Departments of Physiology, University of Birmingham and University of Edinburgh

In the isolated guinea-pig's lungs, perfused through the pulmonary artery with modified Ringer or Tyrode solution:—

1. Excitation of the cervical vagi, or injection of acetylcholine, causes bronchoconstriction and vasoconstriction. These effects are abolished by atropine but are unaffected by eserine. Acetylcholine caused vasodilatation in one experiment only.

2. In one out of four experiments excitation of the stellate ganglion caused vasoconstriction. Injection of adrenaline produces vasoconstriction and, if the tone of the bronchial muscles is already high, bronchodilatation.

3. During rhythmic inflation bronchoconstriction diminishes flow and bronchodilatation increases it. During the action of a drug affecting both bronchi and blood-vessels two mechanisms are responsible for the final effect upon the blood-vessels: (a) the action of the drug upon the blood-vessels and their peripheral elements, and (b) the mechanical forces exerted on the blood-vessels as a result of concomlitant changes in bronchial calibre. The resultant effect is the algebraic sum of the two effects.

4. Eserine causes bronchoconstriction and vasoconstriction in atroponished preparations.

We wish to express our thanks to Professor I. de Burgh Daly for suggesting this work and for his advice and encouragement throughout.

The expenses of this research were in part defrayed by a grant to one of us (B. N.) from the Moray Endowment Committee, to whom we express our thanks.