| Effects of Norepinephrine on the Mechanoreceptors of the Urinary Bladder in the Cat. |
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Hyun Ju Oh, Yoo Jin Kang, Sun Seek Min, Jong Moon Hwang, Seo Eun Lee, Young Wook Yoon, Hee Chul Han, Seung Kil Hong |
1Department of Anesthesiology, Gachon Medical School, Incheon.
2Department of Anesthesiology, College of Medicine, Catholic University, Seoul.
3Department of Physiology, College of Medicine and Neuroscience Research Institute, Korea University, Seoul.
4Department of Lifetime Sport and Leisure, Sang Myung University, Cheon-an, Korea. |
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| Abstract |
BACKGROUND
Recent findings suggest that a coupling between the somatic and sympathetic nervous system is critical not only for the development but also for the maintenance of pain behavioral changes. However, studies on the effect of sympathetic efferent system on sensory receptors in the visceral organ that is more dependent on the autonomic nervous system are lacking. This study examined whether norepinephrine (NE) had an influence on the mechanoreceptors in the feline urinary bladder.
METHODS
Ten adult male cats were used and anesthetized with alpha-chloralose and artificially ventilated. A cannula with the pressure transducer was inserted through the urethra to apply mechanical stimuli and monitor the pressure of bladder. A tiny cannula inserted into the bilateral side branches of vesical arteries were used as a route for a NE (10A.M 9:40 01-10-08 bilaterally) injection. Nerve fiber recordings were obtained from the distal stump of the pelvic nerve.
RESULTS
After the NE injection, the response of mechanoreceptors (n = 13) to the isotonic pressure stimulus (50 - 60 mmHg) decreased significantly (p < 0.05) in terms of sensitivity (i.e., ratio of nerve activity change to urinary bladder pressure change). The responses to pressure stimuli after an injection of an alpha1 adrenoceptor blocker (terazosin) reversed the effect of NE. The responses of mechanoreceptors to isotonic pressure stimulus were not affected significantly by NE with preinjection of an alpha2 adrenoceptor blocker (yohimbine).
CONCLUSIONS
These results suggest that NE may have influence on the sensitivity of mechanoreceptors in the normal feline urinary bladder via an alpha1 adrenoceptor. |
| Key Words:
Receptors: adrenergic; mechanoreceptor; sensory; Sympathetic nervous system: norepinephrine; terazosin; yohimbine |
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