On vaso-motor nerves in the pulmonary circuit

To test the existence of vaso-motor nerves in the pulmonary circuit, the following method was devised : The inlet tube of the stromuhr, recently exhibited by the author before this society, 1 was connected with a receptacle containing Ringer's solution and the outlet tube with a button cannula, to be inserted subsequently into the pulmonary artery of dogs. The chest wall having been resected, loose ligatures were placed around the nerves in the vicinity of the ganglion stellatum and the pulmonary artery. A cannula was inserted into the appendix of the left auricle.

The procedure was as follows: Long forceps-clamps were quickly placed upon the central portion of the pulmonary artery, and transversely across the left auricle close to its junction with the left ventricle. The button cannula having been inserted into the pulmonary artery distally to the clamp, the blood-vessels of the lungs were then supplied with circulating fluid from the receptacle and drained by way of the cannula in the left auricle. Thus, all influences of the heart which might have disturbed vaso-motor reactions in the pulmonary circuit were excluded.

A change in the flow directly attributable to vaso-motor influences, could not be obtained by stimulation of any of the afore-said nerves. Stimulation of the vagus in the neck, as well as centrally and distally to the ganglion stellatum, was ineffective.

In view of these negative results, it seemed advisable to test the influence of adrenalin upon the flow through the pulmonary blood-vessels. A T-tube was inserted between the stromuhr and the button cannula, through which solutions of different strengths were injected. In spite of the fact that these solutions had produced decided vaso-motor reactions in other parts of the body a few minutes previous to these experiments, they remained ineffective when introduced into the pulmonary circuit.