The density and distribution of endothelin 1 and endothelin receptor subtypes in normal and diabetic rat corpus cavernosum.
OBJECTIVE
To investigate the density and distribution of endothelin 1(ET-1) and endothelin receptor subtypes in rat cavernosal tissue, and to assess any changes brought about by the onset of diabetes mellitus (DM).


METHODS
Hyperglycaemic non-ketotic diabetes mellitus was induced in five rats using streptozotocin (STZ). Two months later the penises were excised and stored at -70 degrees C. Longitudinal serial sections (6 microns) were cut using a cryostat and thaw- mounted onto gelatinized microscope slides. Low and high resolution autoradiographs were taken using radioligands for ET-1 and endothelin A (ETA) and endothelin B (ETB) receptors and the autoradiographs analysed densitometrically. These results were compared with those from five age-matched control rats.


RESULTS
ET-1 and ETA receptor binding was primarily localized to the endothelium lining the cavernosal lacunar spaces: trabecular corporeal smooth muscle was much less intensely stained. No ETB receptor binding could be demonstrated, but increased binding of ET-1 and ETA receptors was seen in the diabetic cavernosal tissue.


CONCLUSIONS
ET-1 and ETA receptor binding is increased in diabetic rat cavernosal tissue. A reduction in receptor linked nitric oxide (NO) release has previously been reported in diabetic rats. This finding may provide an explanation for the upregulation of ET-1 and ETA receptor binding in the diabetic rat.
Bell
C R
CR
Department of Urology, Royal Free Hospital and School of Medicine, London, UK.
Sullivan
M E
ME
Dashwood
M R
MR
Muddle
J R
JR
Morgan
R J
RJ
D000818:Animals; D001345:Autoradiography; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D016232:Endothelins / Q000378:metabolism*; D008297:Male; D010413:Penis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017466:Receptors, Endothelin / Q000378:metabolism*
D016232:Endothelins; D017466:Receptors, Endothelin