Mechanism of action of the spasmogenic activity of penthylenetetrazol and of 1,2,3,4-tetrahydroisoquinolines on rat stomach fundus strips.

Spasmogenic activity of penthylenetetrazol (PTZ) and 1,2,3,4-tetrahydro-isochinoline (THI) derivatives was gradually reduced during storage of their solutions as tested on rat isolated stomach fundus strips. Spasmogenic activity of both PTZ and THI derivatives could be modified by prior exposure of the solutions to electrostatic field and to rotating magnetic field or ultrasound treatment. As a consequence of rotating magnetic field treatment, ED50 values for 1-phenyl-6,7-dimethoxy-1,2,3,4-tetrahydro-isochinoline-hydrochloride (S-23), PTZ and for PTZ crystallized from an ether solution of PTZ (PTZA) doubled, i.