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The neuronal and endothelium‐dependent relaxing responses of human corpus cavernosum under physiological oxygen tension last longer than previously expected
Author(s) -
KIMURA KAZUNORI,
KAWANISHI YASUO,
KAGAWA SUSUMU
Publication year - 2004
Publication title -
international journal of urology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 67
eISSN - 1442-2042
pISSN - 0919-8172
DOI - 10.1111/j.1442-2042.2004.00801.x
Subject(s) - oxygen tension , isometric exercise , oxygen , penis , relaxation (psychology) , medicine , acetylcholine , anesthesia , stimulation , anatomy , chemistry , organic chemistry
Background: Intracavernosal oxygen tension varies greatly in the process of erection. Blood extracted from the human penis demonstrates an increase from approximately 30 mmHg Po 2 in the flaccid state to 100 mmHg in the erect state of the penis. In the present study, using these levels as a guide, we investigate how the NO‐dependent relaxation of human corpus cavernosum changed under physiological oxygen tensions ranging from approximately 30 to 100 mmHg. Methods: Human penile tissue specimens were obtained at penile surgery with informed consent from the patients. The preparations were mounted in Krebs solution in an organ bath and the isometric tension was recorded. Krebs solutions of various oxygen tensions were prepared by bubbling 5% CO 2 in N 2 and O 2 . The NO‐dependent relaxation caused by electrical field stimulation (EFS) and acetylcholine (ACh) was studied, and the amplitude and duration of relaxation evaluated. Results: The amplitude of relaxation induced by EFS was significantly decreased under physiological oxygen tension conditions ( P < 0.01). The duration of the relaxant response induced by EFS and ACh was significantly prolonged in physiological oxygen tension conditions than in high oxygen tension ( P < 0.01). However, there was no correlation between the duration of relaxation induced by EFS and each physiological oxygen tension level. The duration of relaxation induced by ACh was most prolonged at 60–69 mmHg oxygen tension. Conclusion: Physiologically, the effect of NO may last longer than was previously thought. In addition, it would seem that there is an optimal physiological oxygen tension for maximum ACh‐induced relaxation.