International Urology and Nephrology

, Volume 50, Issue 5, pp 833–838 | Cite as

Effect of pregnancy on cooling tone and rhythmic contractions of the rat urinary bladder

  • Seham Mustafa
Urology - Original Paper



Pregnancy is a physiological alteration that can affect urinary bladder. Cooling of urinary bladder smooth muscle is known as a potent stimulus to micturition due to an increase in muscle tone. The current study investigates the effects of pregnancy on cooling tone and on the rhythmic contractions of the urinary bladder.


Twenty-four rats were used in this study as control group (non-pregnant) and pregnant group (18–20-day pregnancy). Isolated rat urinary muscle strips were suspended in organ baths containing Krebs’ solution for isometric tension recording.


Cooling from 37 to 5 °C induced a rapid and reproducible increase in basal tone, proportional to cooling temperature. Cooling also increased the rhythmic activity (amplitude and frequency) at 30 and 25 °C, then decreased at 20 °C, and abolished at 15–5 °C. These responses were more pronounced in pregnant group than in control group. Rhythmic contractions were abolished in calcium-free, EGTA (1 mM)-containing Krebs’ solution and in the presence of nifedipine, while they were not affected by CPA or TTX in both groups. Our investigation showed that the influx of extracellular calcium is important in inducing the rhythmic contractions.


Pregnancy increases cooling-induced contraction in pregnant rat urinary preparations and its rhythmic contractions including amplitude and frequency than non-pregnant rat. Rhythmic contractions are myogenic in nature and highly extracellular calcium dependent. They may play a crucial role in urinary bladder overactivity and incontinence during pregnancy.


Pregnancy Urinary bladder Cooling Rhythmic contractions Calcium Incontinence 



The author thanks the Faculty of Medicine at Kuwait University for providing the Laboratory and resources needed to complete this study.

Compliance with ethical standards

Conflict of interest

The author declares that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving animals were in accordance with the ethical standards of the Institutional Animal Care and Use Committee of Kuwait University institution at which the studies were conducted.

Human and animals rights

This article does not contain any studies with human participants performed by any of the authors.

Informed consent

Informed consent was obtained from only myself because I am sole author in the study.


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© Springer Science+Business Media B.V., part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Biomedical Sciences, College of NursingPublic Authority for Applied Education and TrainingSafatKuwait

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