Effect of double distillation in bioassay of acetylcholine using chicken ileum

Abstract BACKGROUND: The purity of physiological salt solutions used in bioassays can influence the biological responses of isolated tissues. The acetylcholine bioassay on chicken ileum is a standard model for assessing drug efficacy and potency. AIM: This study aims to evaluate whether the purity of water (single vs. double distilled) used in preparing physiological salt solution affects the efficacy, potency, and sensitivity of acetylcholine-induced contractions in isolated chicken ileum. METHODOLOGY: Isolated chicken ileum was mounted on a Rudolph Magnus apparatus and exposed to increasing concentrations of acetylcholine. Dose–response curves were recorded for tissues suspended in Tyrode’s solution prepared either with single-distilled water or double-distilled water (DDW). Efficacy (Vmax), potency (Km), and sensitivity were compared between groups. RESULTS: The mean efficacy in the double distillation group turned out to be 71.49 mm, and in the single distillation group, it was 23.5 mm. The mean Km value in the double distillation group was 0.641 μg/ml, and that in the single distillation group was 2.86 μg/ml. Using DDW significantly increased the efficacy ( P = 0.0006) and potency ( P = 0.048) of acetylcholine-induced contractions when compared to the single distillation group. However, there were no significant differences in sensitivity between the groups. CONCLUSION: The use of DDW significantly improved the efficacy and potency of acetylcholine-induced contractions in isolated chicken ileum. This highlights the importance of superior water purification in enhancing the reliability of bioassay outcomes.