RS 67333 HYDROCHLORIDE

Descriptions

Biochem/physiol Actions

RS 67333 is a selective, high affinity (pKi = 8.7 for the 5-HT4 binding site in guinea-pig striatum) partial agonist toward 5-HT4 receptor that relaxes carbachol-contracted rat oesphageal muscularis mucosae ex vivo (pEC50/%reversal = 8.7/50 with RS 67333 vs. 8.2/100 with 5-HT) and induces tachycardia (tachyarrhythmia) of anaesthetized micropigs in vivo (ED50 via i.p. in µg/kg over max heart rate increase in beats/min = 4.9/35 with RS 67333 vs. 3.2/95 with 5-HT). RS 67333 is also reported to show high affinity for sigma receptors (pKi = 8.9/σ1 and 8.0/σ2), while exhibiting much reduced affinity toward a panel of other receptors, including 5-HT1A, 5-HT2A, 5-HT2C, 5-HT3 (pKi ﹤6.4), muscarinic receptors (pKi = 5.2/M1 & 5.3/M2), and adrenoceptors (pKi ﹤6.7 for α1A, α1B, α2A, α2B, β1, β2).