The investigation of erythromycin activity on isolated urinary bladder contractions of hyperthyroid rats

The aim of this study was to clarify the effect of erythromycin on hypertyhroid rat urinary bladder contractile response to characterize its possible potential inhibitor agent. Adult male Wistar albino rats weighing 250-350 g were used in all experiments. Rats were divided into two groups (n = 10 in each group), the first group was given standard rat diet and drinking water (euthyroid), the second group was administered L-thyroxine subcutaneously at a daily dose of 50 µg/100g body weight for 10 days (hyperthyroid). Rat urinary bladders were suspended in a perfusion organ bath.The contractile response as Emax, pD2 and shiftEC50 levels of carbachol (10-3-10-8 M) and potassium (10-2 – 6×10-2 M, KCl) were determined in the absence and presence of erythromycin (10-3, 5x10-4 ve 10-8 M). The contractile responses to carbachol (10-3-10-8 M) in the presence of atropine (10-8 M), verapamil (10-8 M) or in calcium-free Krebs Henseleit solution were also determined in the absence and presence of erythromycin. Treatment of erythromycin significantly reduced the response to carbachol and KCl-evoked contraction. The atropine-resistant component of carbachol evoked contractions were not inhibited in the presence of erythromycin. The contractile response to carbachol was reduced in calcium-free Krebs Henseleit solution and 10-8 M verapamil. Also, erythromycin was added to verapamil 10-8 M, the contractile response to carbachol was inhibited. In conclusion, erythromycin inhibited urinary bladder contractions of hypertyhroid rats by means of the inhibition of calcium influx and the modulation of calcium movement. Keywords: Erythromycin, hyperthyroid, urinary bladder, contraction, inhibition, rat