Mediation of 5-hydroxytryptamine-induced tachycardia in the pig by the putative 5-HT4 receptor.

Intravenous bolus injections of 5-hydroxytryptamine (5-HT; 3, 10 and 30 micrograms kg-1), 5-methoxytryptamine (5-MeO-T; 3, 10 and 30 micrograms kg-1), renzapride (BRL 24924; 3, 10, 30 and 100 micrograms kg-1) and isoprenaline (0.03, 0.1 and 0.

Cardiovascular effects of serotonin agonists and antagonists.

The effects of serotonin (5-hydroxytryptamine; 5-HT) on the cardiovascular system are complex. These effects, consisting of bradycardia or tachycardia, hypotension or hypertension, and vasodilation or vasoconstriction are mediated by three main sets of receptors called 5-HT1-like, 5-HT2, and 5-HT3. In addition, recent findings suggest the participation of a putative 5-HT4 receptor.

The 5-HT1-like receptor mediating reduction of porcine carotid arteriovenous shunting by RU 24969 is not related to either the 5-HT1A or the 5-HT1B subtype.

Using the radioactive microsphere technique in anaesthetized pigs, we studied the systemic and carotid haemodynamic effects of intracarotid infusions (0.3, 1, 3 and 10 micrograms/kg.min) of 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole succinate (RU 24969), a drug with high affinity for 5-HT1A and 5-HT1B recognition sites.

Protective effect of colchicine on acute liver damage induced by carbon tetrachloride.

Pretreatment of rats with colchicine (10 micrograms/day) for 7 days protected against CCl4-induced acute liver damage. CCl4 intoxication was demonstrated histologically and by increased serum activities of glutamic-pyruvic transaminase, alkaline phosphatase and gamma-glutamyl transpeptidase. Furthermore, an increase in liver lipid peroxidation and a decrease in plasma membrane gamma-glutamyl transpeptidase activity were found.