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Integrity of endothelial glycocalyx in hypoxic rat heart capillaries
J Mol Cell Cardiol 22 (Supplement pW28
s,
III) (1990)
UUTNRITKRR BYPOXIANORINTRRWITTRWT ISCRAEHIA INCREASES[“‘I]
RNETKELIN-1 BINDINGTo RATCARDIAC
JianJun Liu, Xin Eua Gu, David J.Casley, Winifred G.Nayler. Departmentof Nedicine University of Relbourne,Austin Eospital, Weidelberg,VIC, 3084, Australia. Rndothelin-l(RT-1) is a newly discoveredvasoconstrictor peptide secreted fros endothelial cells, and thought to be associatedwith cardiovascular diseases. In aninals, injection of ET-1causessuddendeath. In buwans,plasma RTlevels increase in wyocardial infarction, cardioqenic shockand subarachnoidhaenorrbage. Our previous studies have shownthat specific RT-1binding site density (P& is increased after >20 sin ischaemiaand further increased upon reperfusion. Thepresent studies were undertakento deternine whethereither hypoxia, reoxygenation,perfusion under acidotic conditions or %tunningn of the wyocardiuwresewblesischaewiaand reperfusion in increasing cardiac wenbrane[“‘I] binding site density. The results showedthat &., wasincreased after 30 min global ischaeaia, and further increased upon reperfusion, without changesin affinity (K,) or selectivity. Neither three 10 nin episodes of ischaenia separatedby 15 nin perfusion, nor perfusion at pll 6.8 instead of 7.4, nor 60 rin glucose-free hypoxia altered B-, K6 or selectivity. Reoxyqenationafter 60 win hypoxia increasedg, (P
f’w29
INTEGRITY OF ENDOTHELIAL GLYCCCALYX IN HYPOXIC RAT HEART CAPILLARIES Barbara J. Ward, Catherine E. Sarraf*, J. Anthony Firthw. Departments of Anatomy. The Medical College of St. Bartholomew’s Hospital, London EClM 6BQ. *Histopathology, Royal Postgraduate Medical School, London W12 ONN, **Anatomy and Cell Biology. St Mary’s Hospital Medlcal School, London W2 1PG. It has been suggested that the flbre matrix of the endothelial cell glycocalyx is responsible for the permeability properties of continuous capillaries. We have studied the electron microscopic appearance of the glycocalyx of rat heart capillaries In well-oxygenated and hypoxlc hearts as hypoxia is thought to increase permeability. Isolated rat hearts were perfused wlth Krebs solution at 37’ in welloxygenated conditions or for 30 or 60 minutes of hypoxia both with and without albumln. Specific stalning of the glycocalyx was achieved by the addltlon of either of the cationic markers ruthenium red or lanthanum nitrate to the flxatives. The hearts were then processed for electron microscopy. Both markers bound to the capillary basement membranes and to the luminal surface glycocalyx and were frequently observed lining the full length of the Interendothellal clefts. In welloxygenated hearts the glycocalyx appeared as a unlform layer approximately 6-10 nm thick. After hypoxic perfusion it was less regular and more flocculent In appearance. We conclude that changes In the structure of the glycocalyx may play a part In changes in permeablllty. Supported by the British Heart Foundation.
PW30
INCUBATION WITH ENDOTOXIN (ETX) INDUCES VASCULAR HYPOREACTIVITY WHICH IS REVERSED BY NGYONOMETHYL-L-ARGININE (L-NMMA) lngrid Fleming, Gillian A. Gray, GBraldine Julou-Schaeffer, James R. Parrati and Jean-Claude Stoclet. Lab de Phannacodynamie. Univ Louis Pasteur de Strasbourg. F67401 Illklrch, France. The present study examines the effect of ETX-induced hyporeactiviiy in vitro. Incubation of rat aortic rings, with endothelium removed, for 5 h in culture medium containing ETX (100 ng ml-l) resulted in reduced contractile responsiveness to noradrenaline (NA, maximum contraction was 1.77M.37 in ETX-treated rinas COl’IlDar~d to 3.81fi.4i o tension/mg in control tissue, P.cO.05). Inclusion of indomethacin (110 pM) ‘during contractile experiments was without effect but prsincubation with L-NMMA (300 PM), an inhibitor of nitric oxide (NO) production from L-arginine, restored contractile responsiveness to 3.6oM.25 g tension/mg tissue in ETX-treated rings without alterina the response in control tissue (3.43ti.23 g tension/mg tissue). The effect of L-NMMA was over&me by addition of L-arginine (1‘mM). This-agrees with results obtained previously ex vivo and in vivo. Thus, even in the absence of functional endothelium ETX is capable of activating NO production in vascular tissue in vitro, resulting in vascular hyporeactivity. This research was supported by the Comission of the European Communities (grant number ST2J-0457-6). s.10
s,
III) (1990)
UUTNRITKRR BYPOXIANORINTRRWITTRWT ISCRAEHIA INCREASES[“‘I]
RNETKELIN-1 BINDINGTo RATCARDIAC
JianJun Liu, Xin Eua Gu, David J.Casley, Winifred G.Nayler. Departmentof Nedicine University of Relbourne,Austin Eospital, Weidelberg,VIC, 3084, Australia. Rndothelin-l(RT-1) is a newly discoveredvasoconstrictor peptide secreted fros endothelial cells, and thought to be associatedwith cardiovascular diseases. In aninals, injection of ET-1causessuddendeath. In buwans,plasma RTlevels increase in wyocardial infarction, cardioqenic shockand subarachnoidhaenorrbage. Our previous studies have shownthat specific RT-1binding site density (P& is increased after >20 sin ischaemiaand further increased upon reperfusion. Thepresent studies were undertakento deternine whethereither hypoxia, reoxygenation,perfusion under acidotic conditions or %tunningn of the wyocardiuwresewblesischaewiaand reperfusion in increasing cardiac wenbrane[“‘I] binding site density. The results showedthat &., wasincreased after 30 min global ischaeaia, and further increased upon reperfusion, without changesin affinity (K,) or selectivity. Neither three 10 nin episodes of ischaenia separatedby 15 nin perfusion, nor perfusion at pll 6.8 instead of 7.4, nor 60 rin glucose-free hypoxia altered B-, K6 or selectivity. Reoxyqenationafter 60 win hypoxia increasedg, (P
f’w29
INTEGRITY OF ENDOTHELIAL GLYCCCALYX IN HYPOXIC RAT HEART CAPILLARIES Barbara J. Ward, Catherine E. Sarraf*, J. Anthony Firthw. Departments of Anatomy. The Medical College of St. Bartholomew’s Hospital, London EClM 6BQ. *Histopathology, Royal Postgraduate Medical School, London W12 ONN, **Anatomy and Cell Biology. St Mary’s Hospital Medlcal School, London W2 1PG. It has been suggested that the flbre matrix of the endothelial cell glycocalyx is responsible for the permeability properties of continuous capillaries. We have studied the electron microscopic appearance of the glycocalyx of rat heart capillaries In well-oxygenated and hypoxlc hearts as hypoxia is thought to increase permeability. Isolated rat hearts were perfused wlth Krebs solution at 37’ in welloxygenated conditions or for 30 or 60 minutes of hypoxia both with and without albumln. Specific stalning of the glycocalyx was achieved by the addltlon of either of the cationic markers ruthenium red or lanthanum nitrate to the flxatives. The hearts were then processed for electron microscopy. Both markers bound to the capillary basement membranes and to the luminal surface glycocalyx and were frequently observed lining the full length of the Interendothellal clefts. In welloxygenated hearts the glycocalyx appeared as a unlform layer approximately 6-10 nm thick. After hypoxic perfusion it was less regular and more flocculent In appearance. We conclude that changes In the structure of the glycocalyx may play a part In changes in permeablllty. Supported by the British Heart Foundation.
PW30
INCUBATION WITH ENDOTOXIN (ETX) INDUCES VASCULAR HYPOREACTIVITY WHICH IS REVERSED BY NGYONOMETHYL-L-ARGININE (L-NMMA) lngrid Fleming, Gillian A. Gray, GBraldine Julou-Schaeffer, James R. Parrati and Jean-Claude Stoclet. Lab de Phannacodynamie. Univ Louis Pasteur de Strasbourg. F67401 Illklrch, France. The present study examines the effect of ETX-induced hyporeactiviiy in vitro. Incubation of rat aortic rings, with endothelium removed, for 5 h in culture medium containing ETX (100 ng ml-l) resulted in reduced contractile responsiveness to noradrenaline (NA, maximum contraction was 1.77M.37 in ETX-treated rinas COl’IlDar~d to 3.81fi.4i o tension/mg in control tissue, P.cO.05). Inclusion of indomethacin (110 pM) ‘during contractile experiments was without effect but prsincubation with L-NMMA (300 PM), an inhibitor of nitric oxide (NO) production from L-arginine, restored contractile responsiveness to 3.6oM.25 g tension/mg tissue in ETX-treated rings without alterina the response in control tissue (3.43ti.23 g tension/mg tissue). The effect of L-NMMA was over&me by addition of L-arginine (1‘mM). This-agrees with results obtained previously ex vivo and in vivo. Thus, even in the absence of functional endothelium ETX is capable of activating NO production in vascular tissue in vitro, resulting in vascular hyporeactivity. This research was supported by the Comission of the European Communities (grant number ST2J-0457-6). s.10