Evidence for the involvement of endothelin-1 but not urotensin-II in chronic lower limb ischaemia in man.
BACKGROUND
endogenous vasoconstrictor peptides may play a role in the pathophysiology of critical limb ischaemia (CLI). This study investigated endothelin-1 (ET-1) and urotensin-II (U-II) mRNA expression, peptide distribution and ET receptor subtype binding in chronically ischaemic muscle.


METHODS
open muscle biopsies were taken from patients undergoing amputations for CLI and from patients undergoing coronary artery bypass surgery (controls). ET-1 and U-II mRNA expression in muscle biopsies was studied using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). ET-1 and U-II immunohistochemistry was performed on muscle sections and ET receptor binding studied using in vitro autoradiography.


RESULTS
ET-1 mRNA expression was significantly increased in CLI compared to controls (p<0.05) whilst no significant change in U-II expression occurred. ET-1 immunoreactivity was also increased in CLI with no difference in U-II immunostaining observed. ET(B) receptor binding was significantly increased in CLI (median 4, range 1-8 vs 2, range 1-3, dpm x 10(3)/mm(2), p=0.01, Mann-Whitney test) whilst ET(A) receptor binding was not significantly raised. Binding was associated with microvessels and macrophages.


CONCLUSIONS
in CLI, the ET-1 pathway is upregulated but U-II is unaffected. ET-1 may vasoconstrict microvessels and mediate inflammation in chronically ischaemic muscle. ET-1 binding to ET(B) receptors in particular may play an important role in the pathophysiology of CLI underscoring the therapeutic potential of ET(B) receptor antagonists in the management of CLI.
Tsui
J C S
JC
Department of Surgery, Royal Free and University College Medical School, Royal Free Campus, Pond Street, London NW3 2QG, UK.
Baker
D M
DM
Biecker
E
E
Shaw
S
S
Dashwood
M R
MR
D000368:Aged; D000369:Aged, 80 and over; D000671:Amputation, Surgical; D001345:Autoradiography; D016022:Case-Control Studies; D002908:Chronic Disease; D019332:Endothelin-1 / Q000378:metabolism*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007511:Ischemia / Q000378:metabolism* / Q000601:surgery; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric; D015854:Up-Regulation; D014579:Urotensins / Q000378:metabolism*
D019332:Endothelin-1; D012333:RNA, Messenger; D014579:Urotensins; C029677:urotensin II