Perioperative Plasma Endothelin-1 and Big Endothelin-1 Concentrations in Elderly Patients Undergoing Major Surgical Procedures

Endothelin receptor antagonists

Hormone refractory prostate cancer remains true to its middle name: it is largely refractory to attempts to delay its progression. New targets and new therapies are demanded. Through a review of the available literature on endothelin and several preclinical observations, the endothelin axis has emerged as one such target. In phase II and III clinical trials of atrasentan, a potent and selective endothelin receptor A subtype (ET(A)) antagonist, disease progression was delayed in some men. This well tolerated, oral agent may help convert advanced prostate cancer to a more chronic disease. This review will discuss the endothelin axis, preclinical rationale and some of the available clinical trial data on this promising new approach.

Comparison of the role of endothelin, vasopressin and angiotensin in arterial pressure regulation during sevoflurane anaesthesia in dogs

BACKGROUND

In this study we aimed to clarify the role of endothelin in arterial pressure regulation during anaesthesia with increasing concentrations of sevoflurane (1-3 MAC) and compare it with those of vasopressin and angiotensin.

METHODS

After an awake control period, on different days, six dogs underwent each of the following four interventions: sevoflurane anaesthesia alone (1-3 MAC), sevoflurane after block of either endothelin receptors using tezosentan (3 mg kg(-1) followed by 3 mg kg(-1) h(-1)), vasopressin V(1a) receptors using [d(CH(2))(5)Tyr(Me(2))]AVP (40 micro g kg(--1)) or angiotensin receptors using losartan (6 mg kg(-1) h(-1)). Plasma concentrations of endothelin, big endothelin, vasopressin and renin were measured. Effects of sevoflurane in the presence and absence of the respective receptor block were analysed and compared using analysis of variance for repeated measures (ANOVA followed by Fisher's PLSD (protected least significant difference) (P<0.05)).

RESULTS

Mean arterial pressure decreased in a dose-dependent manner with sevoflurane during all interventions. At 1 MAC, this decrease was greatest during angiotensin receptor block (mean (SEM), -41 (3) mm Hg), intermediate during vasopressin and endothelin receptor block (-31 (4) and -30 (2) mm Hg respectively), and least during sevoflurane alone (-24 (3) mm Hg). The course of systemic vascular resistance mirrored the course of arterial pressure, while cardiac output did not differ between groups. Plasma concentrations of endothelin, big endothelin and renin did not change during any intervention, whereas vasopressin concentration increased from approximately 0.5 to 40 ng litre(-1) at 3 MAC as arterial pressure decreased in all groups.

CONCLUSIONS

At 1 MAC, angiotensin attenuated the decrease in arterial pressure during sevoflurane anaesthesia more than endothelin and vasopressin. However, at higher MAC only vasopressin was specifically activated to partly compensate for the arterial pressure decrease.

Changes in plasma endothelin-1 after elective cesarean section in women with preeclampsia and the relationship to thrombocytopenia

OBJECTIVE

The aim of this study was to clarify the time course of plasma endothelin-1 levels and platelet counts after elective cesarean section in women with preeclampsia, and to investigate the relationship between them postoperatively.

METHODS

We studied 20 patients with preeclampsia and 25 healthy pregnant women without preeclampsia who underwent cesarean section and 20 women without preeclampsia who had vaginal deliveries. The plasma endothelin-1 and platelet counts were measured serially after cesarean section.

RESULTS

1) In patients with preeclampsia, plasma endothelin-1 levels peaked on postoperative day 0 (p<0.05), and remained high, then fell to the preoperative level from day 5. The concentration was lower in healthy pregnant women undergoing cesarean section than in patients with preeclampsia before surgery, but showed a gradual significant increase from postoperative day 0 to postoperative day 3 (p<0.05) before falling. The women who underwent vaginal delivery showed a peak level of endothelin-1 on the day of delivery but this fell rapidly between day 3. 2) Women with preeclampsia showed a negative correlation between plasma endothelin-1 levels and platelet counts after cesarean section (r=0.46, p<0.01), while women without preeclampsia undergoing cesarean and vaginal deliveries did not.

CONCLUSION

Endothelin-1 production is stimulated after cesarean section, which is paralleled with postpartal thrombocytopenia only in patients with preeclampsia.

Raised levels of plasma big endothelin 1 in patients with colorectal cancer

BACKGROUND

The aim was to assess the role of plasma Big Endothelin (ET) 1 levels as a marker of disease presence and stage in colorectal adenocarcinoma.

METHODS

Big ET-1 was measured in the plasma of 37 patients with colorectal cancer. Preoperative systemic plasma levels of Big ET-1 in patients with cancer were compared with levels in 20 age- and sex-matched controls. Portal plasma samples were collected at operation in addition to peripheral venous samples. Immunohistochemical staining for Big ET-1 was performed on a selection of primary tumour specimens and liver metastases.

RESULTS

Median (range) preoperative systemic plasma levels of Big ET-1 were significantly higher in patients with cancer than in controls (1.0 (0.3-9.7) versus 0.2 (0.0-6.0) fmol/ml; P = 0.0001). Intraoperative portal plasma levels of Big ET-1 were significantly higher in patients with Dukes' 'D' disease than in patients with Dukes' A, B and C disease (2.1 (1.4-10.0) versus 1.2 (0.3-6.6) fmol/ml; P = 0. 01). Similarly, systemic plasma levels were significantly higher in patients with Dukes' 'D' disease than in those with localized disease (1.9 (1.2-9.7) versus 1.2 (0.2-8.3) fmol/ml; P = 0.01). The presence of microvascular invasion in the tumour specimens was associated with a significantly raised portal plasma level of Big ET-1 (1.6 (1.5-2.1) versus 1.1 (0.8-1.3) fmol/ml; P = 0.04). Immunohistochemistry localized Big ET-1 to the cancer epithelial cells.

CONCLUSION

The plasma level of Big ET-1 is significantly raised in patients with colorectal cancer. Patients with liver metastases have significantly higher levels than those with localized disease.