Guinea pig vas deferens

Palytoxin (PTX), isolated from the zanthid Palythoa species, caused a rapid contraction followed by a slow phasic contraction of the guinea pig vas deferens. The second component of PTX-induced contraction was markedly inhibited by adrenergic blocking agents, whereas the first component was blocked by ouabain. In pheochromocytoma cells,... 

Assay of Endogenous NE. Endogenous NE release from the guinea pig vas deferens was measured by means of a high pressure-liquid chromatograph with an ODS column and an electrochemical detector as described previously (16). 

Mechanical Response. PTX (5 x 10" to 3 x 10 M) caused a concentration-dependent contraction of the guinea pig vas deferens. The configuration of contractile response indicated the presence of two components, an initial rapid component followed by a second slow component. The first component of the response to PTX was abolished after treatment with Mg (10 mM), Ca -free medium, or ouabain (10 M), but remained almost unaffected by phentolamine (10 M), reserpine, 6-OHDA, atropine, or mecamylamine (10" M). The second component of the response to PTX was also completely inhibited after the incubation in the high or Ca -free medium. Phentolamine, reserpine, or 6-... 

Gordienko DV, Greenwood IA, Bolton TB 2001 Direct visualization of sarcoplasmic reticulum regions discharging Ca2+ sparks in vascular myocytes. Cell Calcium 29 13—28 Imaizumi Y, Torii Y, Ohi Y et al 1998 Ca2+ images and K+ current during depolarization in smooth muscle cells of the guinea-pig vas deferens and urinary bladder. J Physiol (Lond) 510 705-719... 

Guinea pig vas deferens Muscarinic nicotinic or Muscarinic Methacholine/atropine Methacholine/hexamethonium Leach, 1956... 

Leach, G.D.H. (1956). Estimation of drug antagonisms in the isolated guinea pig vas deferens. J. Pharm. Pharmacol. 8 501. 

Ohizumi, Y., Kajiwara, A. and Yasumoto, T., Excitatory effect of the most potent marine toxin, maitotoxin, on the guinea-pig vas deferens, J. Pharmacol. Exp. Ther., Ill, 1, 199, 1983. 

P. Sneddon, D. P. Westfall, J. S. Fedan (1982). Cotransmitters in the motor nerves of the guinea-pig vas deferens electrophysiological evidence. Science 218 693-695. 

In the guinea pig vas deferens H3 receptors are located in the sympathetic nerves and their activation inhibits neurotransmitter release (Luo et al., 1994 Luo and Tan 1994). Contrastingly, in the isolated rat vas deferens both H3 agonists and antagonists were found to be inactive, and the modulation of sympathetic neurotransmission was connected with prejunctional H2 receptors (Poli et al., 1994b). 

Luo, X.X., Tan, Y.H., 1994. Presynaptic histamine Hi- and H3-receptors modulate sympathetic neurotransmission in isolated guinea pig vas deferens. Acta Pharmacol Sin. 15, 60-64. 

Driessen B, Bultmann R, Goncalves J, Starke K (1996) Opposite modulation of noradrenaline and ATP release in guinea pig vas deferens through prejunctional (l-adrenoccptors evidence for the P2 subtype. Naunyn-Schmiedeberg s Arch Pharmacol 353 564-71 Drukarch B, Stoof JC (1990) D2 dopamine autoreceptor selective drugs do they really exist Life Sci 47 361-76... 

Gomez-Ramirez J, Ortiz J, Blanco I (2002) Presynaptic H3 autoreceptors modulate histamine synthesis through cAMP pathway. Mol Pharmacol 61 239-45 Goncalves J, Bultmann R, Driessen B (1996) Opposite modulation of cotransmitter release in guinea pig vas deferens increase of noradrenaline and decrease of ATP release by activation of prejunctional beta-adrenoceptors. Naunyn-Schmiedeberg s Arch Pharmacol 353 184-92 Gonzalez-Islas C, Hablitz J (2001) Dopamine inhibition of evoked IPSCs in rat prefrontal cortex. J Neurophysiol 86 2911-18... 

Breuing EP, Kaminskas R, Kobashi YL, et al. 1987. Effects of sodium and calcium concentrations on the barium chloride-induced electrical and contractile responses of the guinea-pig vas deferens. Braz J Med Biol Res 20 231-242. 

Studies on isolated guinea pig vas deferens tissue have been Interpreted as showing that trypsin can reverse an Insurmountable blockade... 

The P2X- ntagonism by PPADS has been confirmed in a wide range of tissues and cells including guinea-pig vas deferens [57], rabbit urinary bladder detrusor muscle [28], rabbit blood vessels [29], rat mesenteric arterial bed [30] (Table 3), rat isolated perfused kidney [58], rat sympathetic ganglia [59] and xenopus oocytes injected with RNA transcribed from a P2X cDNA clone from rat vas deferens [17]... 

However, cADPR may not be a universal regulator of RyRs in smooth muscle cells. In permeabilized strips of guinea pig vas deferens smooth muscle, cADPR at concentrations as high as 100 iM, in contrast to the effects of IP3 and caffeine, failed to contract these preparations (Nixon et al., 1994). 

Fujita A, Takeuchi T, Nakajima H, Nishio H, Hata F (1995) Involvement of hetero-trimeric GTP-binding protein and rho protein, but not protein kinase C, in agonist-induced Ca sensitization of skinned muscle of guinea pig vas deferens. J Pharmacol Exper Therap 274 555-561... 

Hata F, Fujita A, Saeki K, Kishi I, Takeuchi T, Yagasaki O. Selective inhibitory effects of calcium channel antagonists on the two components of the neurogenic response of guinea pig vas deferens. J Pharmacol Exp Ther 1992 263(1) 214—20. 

Diffutin (see above) has pronounced adaptogenic (anti-stress and anti-anxiety) activity, as well as being a mild CNS depressant (barbiturate potentiation). It also has a marked inotropic effect in perfused frog heart, and shows no arrhythmogenic properties. In addition, it potentiates the contractile response of guinea pig vas deferens to catecholamines, without inhibition of the uptake of adrenalin. At 500 mg/kg, diffutin is nontoxic to dogs. The use of Canscora in Indian medicine as a herbal remedy for certain mental disorders is supported by these observations. 

Contrary to CTX, the effects of MTX on cardiac muscle appear not to be mediated by neurotransmitters. The responses of the guinea pig vas deferens to MTX are different from those of CTX. MTX causes a dose-dependent slower contraction of the vas deferens following an initial rapid contraction (Ohizumi et al. 

Ohizumi Y, Ishida Y, Shibata S (1982) Mode of action of the ciguatoxin induced super sensitivity in the guinea pig vas deferens. J Pharmacol Exp Ther 221(3) 748-752. 

Ohizumi, Y., and S. Shibata Mechanism of the Excitatory Action of Palytoxin and N-Acetylpalytoxin in the Isolated Guinea-Pig Vas Deferens. J. Pharmacol, exp. Ther. 214, 209 (1980). 

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