Hydrogen sulfide-induced relaxation of the bladder is attenuated in spontaneously hypertensive rats

To compare hydrogen sulfide (H₂S)-induced relaxation on the bladder between normotensive and spontaneously hypertensive rat (SHR), we evaluated the effects of H₂S donors (GYY4137 and NaHS) on the micturition reflex and on the contractility of bladder tissues. We also investigated the content of H₂S and the expression levels of enzymes related to H₂S biosynthesis [cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (MPST), and cysteine aminotransferase (CAT)] in the bladder.

Eighteen-week-old male normotensive Wistar rats and SHRs were used. Under urethane anesthesia, the effects of intravesically instilled GYY4137 (10^-8, 10^-7 and 10^-6 M) on the micturition reflex were evaluated by cystometry. The effects of NaHS (1 × 10^-8-3 × 10^-4 M) were evaluated on carbachol (10^-5 M)-induced pre-contracted bladder strips. Tissue H₂S content was measured by the methylene blue method. The expression levels of these enzymes were investigated by Western blot.

GYY4137 significantly prolonged intercontraction intervals in Wistar rats, but not in SHRs. NaHS-induced relaxation on pre-contracted bladder strips was significantly attenuated in SHRs compared with Wistar rats. The H₂S content in the bladder of SHRs was significantly higher than that of Wistar rats. CBS, MPST and CAT were detected in the bladder of Wistar rats and SHRs. The expression levels of MPST in the SHR bladder were significantly higher than those in the Wistar rat bladder.

H₂S-induced bladder relaxation in SHRs is impaired, thereby resulting in a compensatory increase of the H₂S content in the SHR bladder.