The influence of pH on the cardiac depressant action of tobramycin.

Tobramycin, like other aminoglycoside antibiotics, is a basic compound which causes a reduction of cardiac contractile force and inhibits the inotropic action of calcium. Its antagonistic action towards calcium had been analysed at different pH values of the solution bathing the rat left atrium. The isometric tension of the electrically driven atrium (4 Hz, 2 ms, supramaximal voltage) in response to cumulative increase in the bath calcium concentration (2.

The relaxing response of the isolated rat duodenum to nicotine.

1. The relaxing responses of the atropine-treated isolated rat duodenum to 12 microM nicotine (N) and transmural electrical stimulation (S) have been compared. 2.

The peripheral analgesic effect of morphine, codeine, pentazocine and d-propoxyphene.

The prostaglandin hyperalgesia and tail immersion tests were used to evaluate the analgesic action of morphine, codeine, d-propoxyphene and pentazocine following intraperitoneal, intraplantar and intracerebroventricular administration to rats. In the prostaglandin hyperalgesia test, all drugs produced a dose-dependent analgesia by the various routes. The rank order of potency after intraperitoneal administration was morphine (100) greater than d-propoxyphene (4) greater than pentazocine (2) greater than codeine (1).

Prostaglandin hyperalgesia, V: a peripheral analgesic receptor for opiates.

Prostaglandin E2 injected in the rat paw causes hyperalgesia which is antagonized by local injections of opiate and opiate antagonists. In the present investigation in rats it is shown that naloxone has an analgesic effect at doses as low as 2 micrograms/site, injected into the rat hind paw. At a dose that has no analgesic effect (1 microgram/site) naloxone antagonized the analgesia produced by either local or systemic administration of morphine.