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Uroguanylin Increases Frequency and Amplitude of Guinea‐pig Bladder Spontaneous Contractility
Author(s) -
Fonteles Manassés,
Pereira Eduardo,
Santos Claudia,
Nascimento Nilberto
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.933.6
Subject(s) - medicine , endocrinology , contractility , agonist , tetrodotoxin , guanethidine , chemistry , stimulation , receptor
Uroguanylin (UGN) is a diuretic and natriuretic peptide synthesized mainly in the gut and kidney and stored as proUGN. Uroguanylin is excreted intact in the urine derived from both enteric and renal proUGN. Nevertheless, its effects on the ureter or bladder contractility are not known. We have probed the effect of cumulative concentrations of uroguanylin (10 ‐9 M to 3x10 ‐6 M) in electrically driven ureter or in the spontaneous contractions of the guinea‐pig bladder. Tissues were mounted vertically as strips in 5 ml organ baths for isometric recordings.UGN, a GC‐c agonist, increased bladder motility in a concentration‐related fashion and achieved a maximal effect of 130.3%. The atrial natriuretic peptide (GC‐A agonist), C‐type natriuretic peptide (GC‐B agonist) or sodium nitroprusside (sGC activator) only marginally increased bladder motility by 15.6%, 19.8% and 16.6%, respectively. The unspecific GC antagonist, isatin, completely blocked the effects of UGN (130.5% UGN vs. 6.5% UGN+isatin; p<0.05). This effect was also blocked by tetrodotoxin (TTX), a neuronal sodium channel blocker and by atropine. UGN also increased the frequency of the spontaneous contractions by 52.4% (p<0.01 vs. control). Similarly, neither ANP, CNP nor SNP were able to affect the frequency of bladder contractions. Isatin also completely blocked the effects of UGN on the frequency of contractions (52.4% vs. 4.3%; p<0.001). UGN did not affect the muscle contractions induced by electrical field stimulation (80V;5ms, 10Hz) in both ureter or bladder. Therefore, the effects of UGN are pre‐synaptic, cGMP‐independent and probably dependent on increased release of acetylcholine. A depolarizing effect of UGN was previously shown.