The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors

Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [3H]granisetron (Ki = 6.76 µM) and G-FL (Ki = 4.90 µM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 µM, and competed with G-FL with a Ki of 7.94 µM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 µM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects.

Arabidopsis ent-Kaurene Oxidase Catalyzes Three Steps of Gibberellin Biosynthesis

The Arabidopsis GA3 cDNA was expressed in yeast (Saccharomyces cerevisiae) and the ability of the transformed yeast cells to metabolize ent-kaurene was tested. We show by full-scan gas chromatography-mass spectrometry that the transformed cells produce ent-kaurenoic acid, and demonstrate that the single enzyme GA3 (ent-kaurene oxidase) catalyzes the three steps of gibberellin biosynthesis from ent-kaurene to ent-kaurenoic acid.

Australia's greatest need : with an introductory note by the Archbishop of Brisbane /

"Errata": slip inserted.

Modern Europe from the fall of Constantinople to the establishment of the German Empire, A.D. 1453-1871.

v. 1. 1453-1530.--v. 2. 1521-1598.--v. 3. 1593-1721.--v. 4. 1714-1796.--v. 5. 1794-1871.

Mémoires sur les fiévres et sur la contagion /

Mode of access: Internet.

Essai sur les maladies des européens dans les pays chauds et les moyens d'en prévenir les suites : suivi d'un appendice sur les fièvres intermittentes & d'un mémoire qui fait connoitre une méthode simple pour dessaler l'eau de mer /

Índice.

Traité du scorbut, divisé en trois parties : contenant des recherches sur la nature, les causes & la duration de cette maladie ; avec un tabbleau chronologique & critique de tout ce qui a paru sur ce sujet /

Mode of access: Internet.

An essay on the government of children : under three general heads, viz. health, manners, and education /

Mode of access: Internet.

The general state of medical and chirurgical practice exhibited : showing them to be inadequate, ineffectual, absurd, and ridiculous ... /

Mode of access: Internet.

Voyage aux sources du Nil, en Nubie et en Abyssynie, pendant les années 1768, 1769, 1770, 1771 /

El tomo 14 es: Quatre voyages dans le pays des Hottentots et la Cafrerie, en 1777, 1778 & 1779 / par... William Paterson. Es la traducción de la obra cuya primera edición es : A narrative of four journeys into the country of the Hottents and Caffraria / by William Paterson. - London : printed for J. Johnson, 1789.

Lectures sur l'histoire et les principes du commerce chez les anciens /

Antep.

Oeuvres complètes de John Hunter /

Mode of access: Internet.

Oeuvres complètes de John Hunter /

Mode of access: Internet.

Oeuvres complètes de John Hunter /

Mode of access: Internet.