Pardaxin produces postjunctional muscle contraction in guinea‐pig intestinal smooth muscle

Abstract

The action of pardaxin (PX), a toxin isolated from the secretion of the Red Sea flatfish, Pardachirus marmoratus, was studied on longitudinal muscle of guinea‐pig ileum. Pardaxin contracted the ileum and subsequently abolished muscle contraction to 5‐hydroxytryptamine (5‐HT), but did not affect the responses to acetylcholine (ACh) and substance P(SP). Pardaxin‐induced contraction was only partially suppressed by atropine and not affected by tetrodotoxin or morphine. Preparations desensitized to 5‐HT or SP responded normally to pardaxin. Pardaxin‐induced contractions were normal in K+‐depolarizing Krebs Ringer solution and not affected by black widow spider venom. It is concluded that the pardaxin‐induced muscle contractions are not mediated through the release of neurotransmitters and do not involve 5‐HT, SP or ACh receptors, but are due to a direct action on the muscle contractile mechanism.

The FISH VENOM TOXINS: NATURAL SOURCE OF PHARMACEUTICALS AND THERAPEUTIC AGENTS “PHARMACEUTICAL AND THERAPEUTIC USES OF FISH VENOM TOXINS

“…Its secondary-structure laminated analogs show 25-80% more alpha-helical content in 40% CF3CH2OH/water than their non-animated form [65]. Pardaxin produces postjunctional muscle contraction in guinea-pig intestinal smooth muscle could be used for drug development [66] (table 4) ( fig. 1 and 2).…”