A direct inhibitory effect of erythromycin on rat urinary bladder smooth muscle

Aviram Nissan*, Nadeer Maudlej, Nahum Beglaibter, Yuval Haskel, Herbert R. Freund, Menachem Hanani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Erythromycin (EM) exerts a dual effect on the contractility of smooth muscle. An excitatory effect mediated via motilin receptors is expressed mainly in the smooth muscle of the stomach and duodenum. The other, a direct inhibitory effect mediated via an unknown mechanism, has been described in guinea-pig and human gallbladder, in the longitudinal smooth muscle of the guinea-pig small intestine and in bronchial smooth muscle. In the present study, the effect of EM on the isolated urinary bladder of the rat was examined using isometric force measurements. The muscarinic agonist carbachol evoked contractions that were reduced by EM in a concentration-dependent manner; at 5 x 10-4 M by 46% [from 1.04 ± 0.42 gm. to 0.56 ± 0.22 gm., (p <0.001)] and at 10-3 M by 57% [from 1.04 ± 0.42 gm. to 0.45 ± 0.20 gm., (p <0.001)]. The inhibitory effect of EM was not altered by the nerve blocker tetrodotoxin. Electric field stimulation of 0.5 Hz, 1 Hz, and 2 Hz contracted the urinary bladder. Erythromycin at 5 x 10-4 M reduced the contractions evoked at 0.5 Hz by 15% [from 0.60 ± 0.22 gm. to 0.51 ± 0.20 gm., (p = 0.004)] and at 10-3 M by 23% [from 0.60 ± 0.22 gm. to 0.46 + 9.12 gm., (p <0.001)]. Erythromycin failed to affect the contractions evoked by bradykinin, phenylephrine or substance P. It is concluded that EM has a direct inhibitory effect on the rat urinary bladder smooth muscle.

Original languageEnglish
Pages (from-to)1006-1009
Number of pages4
JournalJournal of Urology
Volume161
Issue number3
DOIs
StatePublished - Mar 1999
Externally publishedYes

Keywords

  • Bladder
  • Erythromycin
  • Muscle contraction
  • Rat
  • Smooth muscle

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