Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Addition of sialidase or p38 MAPK inhibitors does not ameliorate decrements in platelet in vitro storage properties caused by 4 °C storage

BACKGROUND AND OBJECTIVES

Bacterial proliferation is inhibited in platelets (PLTs) stored at refrigerated temperatures, but also dramatically decreases PLT in vivo survival. Recent studies have demonstrated that cold temperature (CT) stored PLTs secrete sialidases upon re-warming, removing sialic acid from the PLT surface, which may be responsible for clustering of GPIbα and PLT clearance from circulation. In this study, the influence of a sialidase inhibitor or a p38 MAP kinase inhibitor was evaluated in units stored at 4 °C.

MATERIALS AND METHODS

After collection of a single Trima apheresis unit (n = 12), PLTs were aliquoted into four 60-ml CLX storage bags. One bag was stored at 20-24 °C (RT) with continuous agitation; a second bag was stored at 4 °C without agitation; a third bag was held at 4 °C without agitation with sialidase inhibitor, a fourth bag was incubated at 4 °C with a p38 MAPK inhibitor without agitation.

RESULTS

Beginning from Day 1, all in vitro PLT parameters were adversely affected by CT compared to those of RT. Similar in vitro storage properties were observed in CT PLT in the presence or absence of sialidase or p38 MAPK inhibitors. P38 MAPK phosphorylation inhibition was not observed at CT. Decrease of sialidase activity was observed for 2 days in PLTs stored in additive solution but not in plasma.

CONCLUSION

Addition of either sialidase or p38 MAPK inhibitors do not improve any in vitro parameters of PLTs stored at 4 °C in 100% plasma.

Evaluation of in vitro storage properties of apheresis platelets suspended in a bicarbonate-containing additive solution with low levels of plasma and stored with a 24-hour interruption of agitation

BACKGROUND AND OBJECTIVES

PLT additive solutions (PAS) are useful for reducing the frequency and/or severity of plasma-associated transfusion reactions. A new PAS solution, PAS-5, containing 5% plasma, maintains in vitro PLT properties during 7-day storage. Periods with interruption of agitation (IA) ≤24 h routinely occur during PLT shipment and do not usually compromise platelet quality. The aim of the study was to evaluate the properties of PLTs stored for 7 days in 95% PAS-5/5% plasma subjected to a 24-h IA.

MATERIALS AND METHODS

Double apheresis Amicus units (n = 12) were collected using a manual PAS-5 addition to hyperconcentrated PLTs. PLT units were equally divided in two containers. Control and test PLTs were stored with continuous agitation at 20-24°C except for 24-h IA period for test units between days 2-3.

RESULTS

During storage, levels of glucose, lactate, mitochondrial membrane potential and aggregation significantly differed in test units compared to those of control. The pH levels of test PLTs were less than those of control units with 7/12 test units having pHs <6·2 on Day 7 compared to 1/12 control units. Morphology score, GP1bα expression, ESC values, superoxide production were also less, and activation was greater in test PLTs than those of control. All other parameters were similar between test and control units.

CONCLUSION

PLTs stored in PAS-5 solution containing 5% plasma with a 24-h IA results in marked decrements in many in vitro PLT quality parameters during 7-day storage.

Endothelin-A-receptor blockade improves renal function and doubles the lifespan of stroke-prone spontaneously hypertensive rats

This study assessed whether the orally active endothelin-A- (ETA) receptor antagonist, BMS 182874 (BMS), affects systolic blood pressure (SBP), renal function and survival in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSPs). Eight-week-old male and female SHRSPs were given a high-salt diet (4% NaCl) (n = 6/group). The treatment groups (n = 6/group), also on a high-salt diet, were administered BMS (40 mg/kg/day) which was mixed in the food. In untreated SHRSPs, mean survival was 136 days (range 96-194 days) in males, and 98 days (range 74-112 days) in females. Treatment with BMS increased survival to 223 days in males (range 129-280 days, p <0.01 vs controls) and 156 days (range 124-180, p < 0.05 vs controls) in females. SBP increased to approximately 240 mmHg in all groups. BMS had no effect on SBP in females and a small, but significant (p < 0.05), SBP-lowering effect in males. In control rats, severe renal disease was evident at 16 weeks (proteinuria, 161 +/- 1.3 mg/day). In the treated group, development of proteinuria was significantly delayed (13 +/- 0.5 mg/day at 16 weeks). In conclusion ETA-receptor antagonism prolongs survival and improves renal status, but has little effect on the progression of hypertension. These data suggest that interruption of the endothelin (ET) system by blockade of ETA-receptors may achieve protection from target-organ damage despite lack of a reduction in blood pressure.

Effect of chronic treatment with two different ET(A) selective endothelin receptor antagonists on blood pressure and small artery structure of deoxycorticosterone acetate (DOCA)-salt hypertensive rats

Chronic treatment with a combined ET(A) and ET(B) endothelin receptor antagonist blunts hypertension development and small artery hypertrophy in deoxycorticosterone acetate (DOCA)-salt treated rats, in which endothelin-1 is overexpressed in endothelial cells of blood vessels. To determine whether ET(A) receptor antagonism played a predominant role in these findings, in this study the effects of two orally active ET(A) selective endothelin receptor antagonists, A-127722.5 and LU 135252, were evaluated on blood pressure and small artery structure in DOCA-salt hypertensive rats. Rats received A-127722.5 (30 mg/kg/day) or LU 135252 (50 mg/kg/day) in their drinking water since induction of hypertension. Whereas three of 10 untreated DOCA-salt hypertensive rats died, in the two treated groups none died and all appeared healthier. Systolic blood pressure of treated DOCA-salt hypertensive rats, measured with the tail cuff method, was lower than that of untreated DOCA-salt hypertensive rats by a mean of 20 mm Hg (P < .01) after 4 weeks of treatment with A-127722.5 and by 14 mm Hg (P < .01) with LU 135252. Cardiac and aortic relative weights were unaffected by treatment with either agent. Small arteries of the mesenteric, coronary, renal, and femoral vasculature, examined under standardized conditions after mounting on a wire myograph, were found to exhibit significant inward hypertrophic remodeling in DOCA-salt hypertensive rats. DOCA-salt hypertensive rats treated with A-127722.5 had a significantly smaller media width and media-to-lumen ratio in the four vascular beds examined, and rats treated with LU 135252 showed these findings in mesenteric and renal small arteries. These results demonstrate that chronic ET(A) selective antagonism induces similar effects to those of combined ET(A)/ET(B) receptor antagonists in DOCA-salt hypertensive rats; namely, mild reduction in development of hypertension and blunting of small artery morphological changes, and also appears to improve survival. These results suggest a role of ET(A) receptors in the endothelin dependent component of blood pressure elevation in DOCA-salt hypertensive rats, and in the small artery morphological changes present in this model of experimental hypertension.

Effect of chronic ETA-selective endothelin receptor antagonism on blood pressure in experimental and genetic hypertension in rats

1. Chronic treatment with a combined ETA/ETB endothelin receptor antagonist has been shown to reduce blood pressure in experimental rat models of hypertension in which endothelin-1 gene overexpression occurs in the walls of blood vessels, particularly small, resistance-sized arteries, but not in those genetic or experimental models of hypertension in which there is no overexpression of vascular endothelin-1. Failure of some experimental models of hypertension to respond to treatment with the combined ETA/ETB endothelin antagonist may be due in part to blockade of vasorelaxant endothelial ETB receptors which could in theory reduce the efficacy of endothelin antagonism. 2. In this study the orally active ETA-selective endothelin antagonists A-127722.5 and LU 135252 were used in chronic experiments on deoxycorticosterone acetate (DOCA)-salt hypertensive rats (which overexpress vascular endothelin-1 and respond with blood pressure lowering to combined ETA/ETB endothelin receptor antagonism), on spontaneously hypertensive rats (SHR) (which do not overexpress vascular endothelin-1 and do not respond with blood pressure lowering to the combined ETA/ETB receptor antagonist), and in 1-kidney 1 clip Goldblatt (1-K IC) hypertensive rats (which present mild overexpression of vascular endothelin-1 but do not respond with blood pressure lowering to the combined ETA/ETB receptor antagonist). Additionally, it has been suggested that interruption of the renin-angiotensin system may sensitize responses to endothelin antagonism. Accordingly, SHR were treated with an angiotensin converting enzyme inhibitor, cilazapril, in addition to the ETA receptor antagonist. 3. Blood pressure of DOCA-salt hypertensive rats was lowered by a mean of 24 and of 27 mmHg (P < 0.01) by A-127722.5 after 4 weeks of treatment, when given orally at two different doses (10 and 30 mg kg-1 day-1), and by 18 mmHg by LU 135252 50 mg kg-1 day-1. 4. SHR treated with A-127722.5 for 8 weeks starting at 12 weeks of age exhibited the same progressive rise in blood pressure as untreated SHR. Addition of cilazapril resulted in similar reduction of blood pressure in A-127722.5-treated and untreated SHR. 5. Treatment of 1-K IC hypertensive rats with the dose of LU 135252 which lowered blood pressure in DOCA-salt hypertensive rats did not cause any reduction in blood pressure relative to untreated rats. 6. These results demonstrate that treatment with either dose of the selective ETA receptor antagonists A-127722.5 or LU 135252 caused reductions in blood pressure similar to those obtained for a combined ETA/ETB endothelin antagonist. Blood pressure was lowered only in hypertensive rats known to overexpress vascular endothelin-1 (DOCA-salt hypertensive rats) but not in those which do not (SHR) or only have mild vascular overexpression of endothelin-1 gene (1-K 1C hypertensive rats). Reduction in activity of the renin-angiotensin system in SHR did not sensitize blood pressure to potential hypotensive effects of an ETA-selective receptor antagonist.

Vascular endothelin-1 gene expression and effect on blood pressure of chronic ETA endothelin receptor antagonism after nitric oxide synthase inhibition with L-NAME in normal rats

BACKGROUND

Vascular expression of the endothelin-1 gene may be associated with severe vascular hypertrophy. Because in rats, inhibition of NO synthase with the L-arginine analogue N omega-nitro-L-arginine methyl ester (L-NAME) induces blood pressure elevation associated with little cardiovascular hypertrophy, we studied vascular endothelin-1 gene expression in L-NAME-treated rats and the effects of chronic endothelin antagonism.

METHODS AND RESULTS

Sprague-Dawley rats received 100 mg.kg-1.d-1 L-NAME in their drinking water for 3 weeks. Systolic blood pressure rose to 189 +/- 3 mm Hg (P < .001 versus control rats). By Northern blot analysis, endothelin-1 mRNA levels were similar in aortas and mesenteric arteries of control and L-NAME-treated rats. The blood pressure of L-NAME hypertensive rats treated with the ETA-selective endothelin receptor antagonist A-127722 for 3 weeks at a low dose (10 mg.kg-1.d-1) and a high dose (30 mg.kg-1.d-1) was not different from that of rats receiving L-NAME but not the endothelin antagonist. Treatment with the ACE inhibitor cilazapril lowered the blood pressure of L-NAME-treated rats equally whether or not they were receiving the ETA antagonist.

CONCLUSIONS

These results indicate that the endothelin system does not participate to an important degree in the mechanisms leading to elevated blood pressure after chronic NO synthase inhibition with L-NAME in normal rats. In the chronic model of L-NAME-induced hypertension, blockade of the renin-angiotensin system does not unmask an endothelin-dependent vasopressor tone. In addition, either NO does not regulate vascular endothelin-1 gene expression or L-NAME exerts an inhibitory effect on endothelin expression in blood vessels.

Effect of endothelin antagonism on blood pressure and vascular structure in renovascular hypertensive rats

To investigate the potential pathogenic role of endothelin in blood pressure elevation and vascular hypertrophy in renovascular hypertensive rats, which present twofold elevations in endothelin-1 mRNA abundance in blood vessels, the response of blood pressure and vascular structure to chronic treatment with the endothelin receptor antagonist bosentan was evaluated. One-kidney, one clip (1K,1C) and two kidney, one clip (2K,1C) Goldblatt hypertensive rats were treated for 2 wk with bosentan (100 mg.kg-1.day-1) in their chow, and systolic blood pressure was measured by the tail-cuff method. Vascular structure was studied in small arteries mounted on a wire myograph. Treatment with bosentan did not result in a significant change in systolic blood pressure or in the structure of small coronary, renal cortical, mesenteric, or femoral arteries in 1K, 1C or in 2K, 1C hypertensive rats. In conclusion, modest (twofold) elevations of endothelin-1 gene expression in blood vessels in renovascular hypertension are not associated with hypotensive responses or regression of vascular hypertrophy during treatment with endothelin antagonists in contrast to what is found in deoxycorticosterone acetate salt hypertensive rats, which exhibit very dramatic increases in endothelin-1 expression (five-to eightfold) and do respond to endothelin antagonism with blood pressure lowering and regression of vascular hypertrophy. These small elevations of vascular endothelin-1 gene expression thus do not appear to indicate the presence of an endothelin component in blood pressure elevation in renovascular hypertension in rats.

Vascular and cardiac overexpression of endothelin-1 gene in one-kidney, one clip Goldblatt hypertensive rats but only in the late phase of two-kidney one clip Goldblatt hypertension

OBJECTIVE

To investigate a model of experimental hypertension that exhibits severe hypertrophy of small blood vessels but in which deoxycorticosterone acetate (DOCA) and salt are absent: the one-kidney, one clip model of Goldblatt renovascular hypertension, which is non-renin-dependent, and compare it with the renin-dependent two-kidney, one clip Goldblatt hypertensive rat, in which additionally vascular hypertrophy is less severe.

METHODS

Endothelin-1 gene expression in blood vessels and in the heart was examined by Northern blot analysis.

RESULTS

After 2 or 4 weeks of application of the silver clip to unilaterally nephrectomized rats, the aorta and mesenteric arteries exhibited a significant increase in the intensity of the 2.3 kb band corresponding to hybridization with endothelin-1 messenger RNA (mRNA) in comparison with results obtained in control unilaterally nephrectomized rats. No increase was noted in the blood vessels of the two-kidney, one clip hypertensive rat at 2 or 4 weeks, but significant increases were found at 8 weeks in aorta, but not in mesenteric arteries. Cardiac abundance of endothelin-1 mRNA was also increased in ventricles and in the left atria of one-kidney, one clip hypertensive rats, but only in the late phase (at 8 weeks) in two-kidney, one clip hypertensive rats.

CONCLUSION

Because one-kidney, one clip hypertensive rats presented severe vascular hypertrophy whereas two-kidney, one clip hypertensive rats only did so in the late phase of hypertension, these results lend further support to there being a relationship between vascular hypertrophy and endothelin-1 vascular overexpression in experimental models of hypertension. They also demonstrate that enhancement of the expression of endothelin-1 gene in blood vessels and in the heart of hypertensive rats may occur in the absence of exposure to DOCA and salt, and that endothelin-1 gene overexpression in experimental hypertension occurs early in non-renin-dependent, volume-expanded models such as the one-kidney, one clip or the DOCA-salt hypertensive rat, but only in the progressively non-renin-dependent late phase of the initially renin-dependent volume-contracted two-kidney, one clip hypertensive rat.

Antihypertensive effect of an endothelin receptor antagonist in DOCA-salt spontaneously hypertensive rats

1. Endothelin-1 gene expression is enhanced in aorta and mesenteric arteries, and possibly other vessels, of deoxycorticosterone acetate (DOCA)-salt hypertensive rats but is normal or reduced in spontaneously hypertensive rats (SHR). Bosentan, a mixed ETA/ETB endothelin receptor antagonist, blunts the development of elevated blood pressure of DOCA-salt hypertensive rats but not in SHR. In this study we investigated whether treatment of DOCA-salt SHR with bosentan would result in blunted rise in blood pressure. 2. SHR, aged 13 weeks, were implanted with silastic containing DOCA and offered 1% saline to drink. Systolic blood pressure was measured by the tail-cuff method. Endothelin-1 mRNA abundance in aorta and mesenteric arteries was measured by Northern blot analysis. Content of immunoreactive endothelin in blood vessels was measured by radioimmunoassay. 3. Systolic blood pressure rose less in bosentan-treated DOCA-salt SHR (to 223 +/- 2 mmHg) in comparison to the untreated rats (241 +/- 1), a small but significant difference (P < 0.001). However, blood pressure of bosentan-treated DOCA-salt SHR was still higher than in age-matched SHR. Endothelin-1 mRNA abundance and content of immunoreactive endothelin were increased in the aorta and the mesenteric arterial bed of DOCA-salt SHR, and were unaffected by treatment with bosentan. 4. These data support the hypothesis of a role of endothelin-1 in blood pressure elevation in this hypertensive model with malignant hypertension. They also support the hypothesis that an antihypertensive effect of the mixed ETA/ETB endothelin receptor antagonist, bosentan, is found when experimental hypertensive animals exhibit enhanced endothelin-1 gene expression in blood vessels.

Effects of ANP, angiotensin, vasopressin, and endothelin on ANP receptors in cultured rat vascular smooth muscle cells

Some evidence suggests homologous and heterologous regulation of atrial natriuretic peptide (ANP) receptors. We have examined the effects of exposure to ANP, angiotensin II (ANG II), arginine vasopressin (AVP), and endothelin (ET), on binding of ANP to cultured rat vascular smooth muscle cells (VSMC) and on guanylate cyclase-coupled and -uncoupled ANP receptors. The latter were studied by examining production of guanosine 3',5'-cyclic monophosphate (cGMP) in response to ANP and binding of ANP to Triton X-100-solubilized VSMC membranes, irreversible cross-linking with disuccinimidyl suberate, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in presence of dithiothreitol, followed by radioautography. Exposure to 100 nmol/l ANP for 18 h reduced ANP sites to 43% of control. However, if acid wash of VSMC membranes at pH 5.0 was performed before binding, no decrease in density of ANP binding sites was detected. On SDS-PAGE, a 130-kDa band bound 42 vs. 46% of 125I-labeled ANP in acid-washed membranes from control vs. cells exposed to ANP; the remainder was bound to a 67-kDa band. ANG II (100 nmol/l), AVP (1 mumol/l), or ET-1 or ET-3 (100 nmol/l) did not produce changes in density of ANP sites or in binding to the 130- and 67-kDa bands. cGMP production in response to ANP showed exaggerated response in ANG II but not in AVP- or ET-treated VSMC. Effect of ANG II was abolished by the ANG II antagonist [Sar1-Ile8]ANG II.(ABSTRACT TRUNCATED AT 250 WORDS)