Amphibian toxins from the skin of <i>Bufo regularis</i> have inhibitory effect on electrically invoked contractile response and bimodal effects on tone of longitudinal muscle of guinea pig ileum

The skins of some amphibians contain potentially bioactive principles that may have pharmaceutical, medicinal, toxicological or chemical importance. In addition, such active principles can be used as tools in biomedical research. The present study aims at isolating and purifying bioactive principles from the skin of Bufo regularis and studying their effect on isolated longitudinal smooth muscle strip of guinea pig ileum. High performance liquid chromatography (HPLC) was used to isolate toad toxins. The effects of crude, semi-purified and purified extracts were tested on longitudinal smooth muscle of guinea pig ileum using organ bath method. Effect of the toxins was studied on electrically-induced contractile response and the basal tone of the longitudinal muscle strip. HPLC purification resulted in four different bioactive components with a λmax UV absorbance pattern of around 295 nm. When tested on guinea pig ileum they had persistent inhibitory effect on the electrically-induced contractile responses. The pattern of effect was initial excitatory followed by long lasting inhibitory effect on tone of longitudinal muscle. The HPLC eluate at 79th min in methanol preparative run corresponding to the eluate at 40th min in the acetonitrile run had the maximum bioactivity. Hence, it was concluded that the skin of B. regularis contains four different components which vary in their potency on isolated smooth muscle strip of guinea pig ileum.Keywords: Bufo regularis, organ bath, longitudinal muscle of ileum, toad toxin, electrical field stimulation

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The effect of ouabain on the guinea pig ileum longitudinal smooth muscle: 1. ATPase activities in a sarcolemma-enriched fraction prepared with the aid of divalent cation depletion of the intact muscle

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y77-162 ◽

1977 ◽

Vol 55 (5) ◽

pp. 1190-1196 ◽

Cited By ~ 3

Author(s):

M. R. James ◽

B. D. Roufogalis

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Atpase Activity ◽

Divalent Cation ◽

Microsomal Fraction ◽

Longitudinal Muscle ◽

Divalent Cations ◽

Guinea Pig Ileum ◽

Longitudinal Smooth Muscle ◽

Intact Muscle

Depletion of divalent cations before fractionation of the longitudinal muscle of the guinea pig ileum yielded a sarcolemma-enriched microsomal fraction free of mitochondria. A major portion of the ATPase activity in the presence of Mg, Na, and K was due to stimulation by Na alone. A further small stimulation by K was demonstrated only in the presence of an activating factor from the 105 000 × g supernatant. Ouabain inhibited only the K activation and had no effect on the Na-stimulated Mg-ATPase.

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K transport and mechanical responses of isolated longitudinal smooth muscle from guinea pig ileum

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1961.200.4.789 ◽

1961 ◽

Vol 200 (4) ◽

pp. 789-793 ◽

Cited By ~ 26

Author(s):

George B. Weiss ◽

Robert E. Coalson ◽

Leon Hurwitz

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Contractile Response ◽

Muscle Tone ◽

Muscle Layer ◽

Smooth Muscle Contraction ◽

Potassium Ion ◽

Guinea Pig Ileum ◽

Potassium Efflux ◽

Longitudinal Smooth Muscle

The longitudinal smooth muscle layer of the guinea pig ileum was isolated in order to investigate its contractile responses and unidirectional K42 fluxes. Pilocarpine (7.5 x 10–6 m), acetylcholine (6.6 x 10–6 m), and a modified Tyrode's solution in which potassium ion was substituted for almost all the sodium ion were employed as excitatory agents. Cocaine (8.5 x 10–4 m) and a calcium-free Tyrode's solution served as inhibitory agents. Smooth muscle tone and potassium efflux of this relatively pure tissue were both increased by all three excitatory substances. Moreover, acetylcholine and pilocarpine produced a decrease in the influx of potassium ion. Bathing the tissue in a calcium-free medium for 1 hour before introducing pilocarpine to the muscle bath eliminated the contractile response that this drug ordinarily produces, but did not diminish appreciably the increase in K42 efflux. These observations are qualitatively similar to results previously obtained in analogous experiments on isolated whole ileum. In addition, cocaine (8.5 x 10–4 m) was found to block the contractile response and about three-quarters of the enhanced K42 efflux elicited by the isotonic potassium solution. It is presumed that cocaine acting at the membrane impedes ion fluxes important for smooth muscle contraction.

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