Faculty of Veterinary Medicine University of Zagreb
Abstract
The present study was undertaken to determine the effects of erythromycin on urinary bladder muscle contractions in hyperthyroid rats. Totally 12 rats were assigned into 2 groups (6 rats in each group), as the control and hyperthyroid rat groups. The contractile responses were determined as Emax and pD2 of carbachol (10-3-10-8 M) and potassium (1-6×10-2 M, KCl) in the absence and presence of erythromycin (10-3; 5×10-4; 10-4 M). The contractile responses to carbachol (10-3-10-8 M) in the presence of verapamil (10-8 M), atropine (10-8 M), or in calcium-free Krebs solution were also determined in the absence and presence of erythromycin (10-3 M). Treatment of erythromycin significantly reduced the response to carbachol and KCl-evoked contractions. Carbachol-evoked contractions were reduced in the presence of atropine, whereas the atropineresistant components of carbachol-evoked contractions were not inhibited in the presence of erythromycin. The contractile response to carbachol was reduced in calcium-free Krebs solution and 10-8 M verapamil. In addition, when erythromycin was added together with verapamil 10-8 M, the contractile response to carbachol was inhibited. In conclusion, erythromycin more effectively inhibited urinary bladder contractions in hyperthyroid rats than the control rats, through calcium movement inhibition.Istraženi su učinci eritromicina na kontrakcije mišića mokraćnog mjehura u hipertireotičnih štakora. Dvanaest štakora bilo je svrstano u dvije skupine, kontrolnu i pokusnu (po šest štakora u svakoj skupini). Kontraktilni odgovor izražen kao Emax i pD2 na karbakol (10-3-10-8 M) i kalij (1-6×10-2 M, KCl) bili su određeni u odsutnosti i prisutnosti eritromicina (10-3; 5×10-4; 10-4 M). Kontraktilni odgovori na karbakol (10-3-10-8 M) u prisutnosti verapamila (10-8 M), atropina (10-8 M), ili u Krebsovoj otopini bez kalcija, bili su također određivani u odsutnosti i prisutnosti eritromicina (10-3 M). Primjena eritromicina značajno je smanjila odgovor na kontrakciju potaknutu karbakolom i kalijevim kloridom. Kontrakcije potaknute karbakolom bile su smanjene u prisutnosti atropina, dok komponente kontrakcija izazvane karbakolom rezistentne na atropin nisu bile inhibirane u prisutnosti eritromicina. Kontraktilni odgovor na karbakol bio je smanjen u Krebsovoj otopini bez kalcija i 10-8 M otopini verapamila. Povrh toga, kontraktilni odgovor na karbakol bio je inhibiran kad je eritromicin bio primijenjen zajedno s 10-8 M verapamilom. Može se zaključiti da je eritromicin učinkovitije inhibirao kontrakcije mokraćnog mjehura hipertireotičnih štakora nego u kontrolnih štakora putem inhibicije kolanja kalcija
