Effects of somatostatin and octreotide on portal-systemic collaterals in portal hypertensive rats.
OBJECTIVE
Somatostatin and its long-acting analogue, octreotide, have been used to cease variceal bleeding with uncertain mechanisms. This study investigated whether somatostatin and octreotide have a direct vasoconstrictive effect on the portal-systemic collaterals of portal-hypertensive rats and potentiate the vasoconstriction induced by endothelin-1 in these vascular beds.


METHODS
The vascular responses of collateral vessels to graded concentrations of somatostatin (10(-9)-10(-5) mol/l), octreotide (10(-10)-10(-6) mol/l), norepinephrine (10(-9)-10(-5) mol/l) and vehicle (Krebs solution) were evaluated in perfused collateral vascular beds of rats with portal hypertension induced by partial portal vein ligation. In addition, the perfusion pressure changes of collateral vessels to endothelin-1 (10(-8) mol/l) in the presence of vehicle(control), somatostatin (10(-6) mol/l) and octreotide (10(-6) mol/l) were tested.


RESULTS
Compared with the vehicle group, norepinephrine significantly increased the perfusion pressure of collateral vessels at concentrations between 10(-7) and 10(-5) mol/l. In contrast, neither somatostatin nor octreotide significantly changed the perfusion pressure. Somatostatin and octreotide significantly enhanced the endothelin-1-induced vasoconstrictive effect on the collaterals.


CONCLUSIONS
Somatostatin and octreotide exert no direct vasoconstrictive effect on the collateral vessels of portal hypertensive rats. In the presence of endothelin-1, somatostatin and octreotide exert a local vasoconstrictive effect on these vascular beds.
Huang
Hui-Chun
HC
Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, No-201, Sec 2, Shih-Pai Road, Taipei 11217, Taiwan, ROC.
Lee
Fa-Yauh
FY
Chan
Che-Chang
CC
Chang
Full-Young
FY
Wang
Sun-Sang
SS
Lin
Han-Chieh
HC
Hou
Ming-Chih
MC
Chen
Chien-Ting
CT
Tai
Chun-Ching
CC
Lai
I-Nien
IN
Lee
Shou-Dong
SD
D000818:Animals; D003097:Collateral Circulation / Q000187:drug effects*; D019332:Endothelin-1 / Q000494:pharmacology; D006490:Hemostatics / Q000494:pharmacology*; D006975:Hypertension, Portal / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D015282:Octreotide / Q000494:pharmacology*; D011168:Portal System / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects
D019332:Endothelin-1; D006490:Hemostatics; D013004:Somatostatin; D015282:Octreotide