Guinea-pig ileum bioassay

A guinea pig ileum bioassay was used to detect and aid in the isolation of a smooth-muscle-contracting substance from the Japanese gorgonian coral Euplexaura erecta [108]. This process led to the isolation of prostaglandin F2a (17) from the MeOH extract of the coral. Its identification was based on comparison with authentic PGF2a and its methyl ester by TLC, and comparison with authentic methyl PGF2a trimethylsilyl ether by mass spectrometry. Because of the nature of the techniques employed, some aspects of the stereochemistry in this isolate of PGF2a remain uncertain. 

In the guinea-pig ileum bioassay, extracts and homogenates of S. mansoni produce spasmogenic activity this activity is abolished with cholinesterase treatment or blocked... 

Guinea Pig Bioassay of GT-3. The application of GT-3 to the guinea pig ileum at 10 ng/ml produced a permanent 50% inhibition in activity. However, this inhibition does not come to a stable level until ninety minutes after the application of the toxin for a fifteen minute interval. We, therefore, expressed the effects... 

Histamine also acts on extravascular smooth muscles to cause contraction or relaxation. Most often, contraction is due to activation of Hj receptors and relaxation to activation of H2 receptors (32). In man, histamine causes contraction of bronchial and intestinal smooth muscles. Histamine-induced contraction of guinea pig ileum is a standard bioassay for histamine. Its effects on smooth muscle of the eye and genitourinary tract are important in some species but not in human ( ). In scombroid poisoning cases. 

Histamine causes contraction of intestinal smooth muscle, and histamine-induced contraction of guinea pig ileum is a standard bioassay for this amine. The human gut is not as sensitive as that of the guinea pig, but large doses of histamine may cause diarrhea, partly as a result of this effect. This action of histamine is mediated by receptors. 

PENK), prodynorphin (PDYN), and pro-opiomelanocortin (POMC) [13-15]. PENK was originally discovered in bovine adrenal cortex and pig brain, where enkephalin biosynthesis was elucidated [13]. It contains one copy of Leu-enkephalin, four copies of Met-enkephalin, and one copy each of a Met-enkephalin C-terminal-extended heptapeptide and octapeptides, all flanked by basic dipeptides, where processing generally takes place. The primary identification of delta opioid receptors was a direct consequence of the discovery of these enkephalins [16]. These peptides were first examined for their potency at opioid receptors present in the guinea pig ileum and mouse vas deferens bioassays. The result of these studies shows that enkephalins are acting at a different receptor in the mouse vas deferens than the guinea pig ileum and this receptor for enkephalins was defined as the elimination of the delta opioid receptor [17]. 

Opioid receptors are found in both the CNS and in the periphery. In the CNS different types of opioid receptors (ja, k, and S receptors see below) exhibit distinct anatomical distributions (see Refs. 68-70 for reviews), and there is considerable species variation in both relative receptor density and receptor distribution. Peripheral receptors mediate some effects of opioids, such as inhibition of gut motility, and for a number of years receptors from tissues such as the guinea pig ileum (GPI) formed the basis of standard bioassays used to assess compounds for opioid activity (see Section 3.2.3.3 below). Peripheral recep-... 

HTg receptors are located on several peripheral organs, and bioassays using the rabbit vagus nerve, the rabbit heart and the guinea-pig ileum have been developed. 

Previous work by Assem (1977) had suggested that the leucocyte histamine release test was a particularly useful diagnostic tool in patients who developed reactions to muscle relaxants. In that work, it was essential to assay the histamine released by a non-biological method (i.e., not on isolated guinea-pig ileum) because of the interference by muscle relaxants with the bioassay. The assay procedure used was chemical, using an automated spectrofluorometric technique (Technicon). Good... 

Many other bioassays have been developed using guinea pig ileum guinea pig atrium, isolated frog nerve fiber crayfish nerve cord and human and mouse blood cell hemolytic tests (Benoit et al. 1986 Dickey et al. 1982 Escalona De Motta et al. 1986 Lewis 1988 Lewis and Endean 1986 Miller et al. 1986 Miya-hara and Shibata 1984 Miyahara et al. 1979). 

Potentiation of bradykinin was measured in bioassay on the isolated guinea pig ileum suspended in Tyrode solution at +37 C and aerated or oxygenated with carbogen. The experiments were performed by first determining the linear dose response range... 

While having no contracting effect on the isolated guinea pig ileum by themselves, the tryptic peptide preparations strongly potentiated the smooth muscle contraction of bradykinin, when assayed in a mixture. To avoid the interference of these peptides in a bioassay of bradykinin separation is easily achieved by ion exchange chromatography on IRC 50 (XE-64) resin by a method described in detail before (14). The broader aspects concerning... 

Histamine can be determined by a fluorometric procedure. Alternatively, it can be estimated by a bioassay which depends on measuring the contraction of a piece of guinea pig ileum.The latter procedure is better adapted to handling large numbers of samples although it is not as specific as the fluorometric procedure. 

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