Morphine and transient lower esophageal sphincter relaxation (TLESR): Relevance of fundic mechanoreceptors

An experimental model for the study of transient lower oesophageal sphincter relaxation and motor function of the proximal stomach in humans

“…Some previous studies of pharmacological agents for transient LOS relaxation have evaluated changes in gastric volume 14,24 or pressure 26 without any formal separation of phasic activity, but we think that our approach is more cautious because different drugs may have different effects on the two components of motility, and the relevance of each component to the triggering of transient LOS relaxation is still obscure: for example, both morphine and erythromycin increase tone, but the former decreases and the latter increases contractions. 18,19 Thirdly, we used isovolumetric distensions. Would our model still be valid during isobaric distensions, i.e.…”

“…The sample size of 12 was calculated using the formula (Z α /2 − Z) 2 σ 2 /( μ 1 − μ 2 ) 2 , 20 where α is the level of significance (0.05), β the power (0.80), σ 2 the estimated variance, and μ 1 − μ 2 the greatest difference between the first and second 30 min‐distension considered acceptable. The estimates of σ 2 and μ 1 − μ 2 were based on data obtained in 24 healthy subjects using this type of distension 18,19 and pharmacological studies of transient LOS relaxations in healthy subjects 21–25 . In particular, we chose a value 1.76 for μ 1 − μ 2 (approximately 40% of the variation from the mean of the 24 subjects) because drugs which reduce the number of reflux episodes by inhibiting transient LOS relaxations decrease the rate of relaxations by > 50%.…”

“…Normative data were obtained by pooling the first distension data of our 12 subjects with those of 24 additional subjects who had received a drug during the second distension 18,19 . The 36 subjects comprised 20 men and had an age range of 21–30 years.…”