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Ischemic preconditioning attenuates postischemic leukocyte adhesion to rat mesenteric venules: Role of adenosine
April t 9 9 5
Intestinal Disorders
• Effects of chronic arterial hypertension on constitutive and induced ICAM-1 expression in the splanchnic organs. S Komatsu, J Pan6s, MA Perry#, JM Russell, DN Granger Dept. Physiology, LSU Medical Center, Shreveport, LA 71130 #University of South Wales, Sydney, Australia Recent reports indicate that the endothelial cell adhesion molecule, ICAM-1 is upregnlated in response to endotoxin to a greater extent in cultured endothelial cells derived from spontaneously hypertensive (SHR) than cells norrnotensive (WKY) rats. it remains unknown whether such a difference occurs in vivo and whether vessels in splancbnic organs exhibit these altered responses in Chronically hypertensive animals. The objectives of this study were to characterize and compare the in vivo expression of ICAM-1 in SHR and WKY rats, under basal conditions and after exposure to endotoxin. Methods: ICAM-1 expression was studied in the splanchnic organs of untreated or eadotoxin-treated SHR and WKY rats at 5 hours after endotoxin administration (5mg/kg i.p.). ICAM-1 expression was measured using a25Ilabeled anti-rat ICAM-1 mAb (1A29), and an isotype matched control mAb: J3~IP-23 (anti-dog ICAM-1) to correct for nonspecific accumulation of the binding mAb. ICAM-1 corrected activity is expressed as (% injected activity ~25I-1A29./g) - (% injected activity 13~I-P-23Ig), Results: Constitutive expression of ICAM-1 was detected in all splanchnic organs. The levels of constitutive expression of ICAM-1 were similar in SHR and WKY. After endotoxin administration ICAM-1 expression significantly increased in all organs except the liver and spleen in both SHR and WKY rats. However, the magnitude of upregu!ation of ICAM- 1 in both the small and the large intestine was significantly lower in SHR than in WKY (small intestine 0.425-+0.020 vs. 0.527-+0.024 %/g, p<0.01; large intestine 0.317_+0.017 vs. 0.423+0.018 %/g, p<0.01, respectively ). No significant differences hi endotoxin-induced ICAM-1 apregulation were noted between the two groups for fiver, spleen, pancreas~ mesentery, and stomach. Conclusions: Chronic arterial hypertension does not affect constitutive expression of ICAM-1 in splanchnic organs, but is associated with a decreased endotoxin-induced upregnlation of the endothelial cell adhesion molecule in the small and large intestine.(Supported by DK43785)
@ ISCHEMIC LEUKOCYTE ADENOSINE of Physiology,
A297
DISCRIMI ANT EFFECTS OF HEMORRHAGIC SHOCK ON PHAGOCYTIC CLEARANCE AND PHAGOCYTIC KILLING BY THE HEPATIC RETICULOENDOTHELIAL SYSTEM ~ , Dajie Wang, ToshJhiko Ma~am~" Andrew Klein and Gregory Bulkley. Dept of Surgery, the Johns Hopkins University, Baltimore, MD We evaluated the quantitative effects of hemorrhagic shock/r~suscitation (S/R) on two disparate components of hepatic reticuloendothelial system (RES) function in male Sprague Dawley rats. Under pentobarbital anesthesia; rats were subjected to hemorrhagic shock such that mean arterial pressure was maintained at 50-x-5 mmHg for 2h, resuscitated by reinfusion and volume loading for 20m, and then followed for 0, 6 and 24h while the rats developed many components of multiple organ failure syndrome. At the above times, E.coli with cytoplasm labeled with ~lCr and DNA labeled with 12SI-UdRwere injected into the femoral vein and the rats euthanized 90m later. Previous
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' t4 C 6 ~ t4 time (hI time (h) time (h) S/R significantly decreased HPC at 0 and 6h, but this returned to normal after 24h. On the other hand, HKE was significantly increased at 0 and 24h, but transiently inlfibited at 611. ConSequently, net hepatic killing of blood-borne E.coli was depressed at 0 and 6h, but substanUaUy upregulated al~er 24h. (Even the anesthesia and instrumentation of sham S/R upregulated HKE and consequently net hepatic killing, without affecting HPC.) These findings quantitatively reflect the differential effects of S/K on two different components of hepatic RES function: phagocytic clearance and phagocytic ldlling efficiency. The net effect on net hepatic killing reflects a combination of these two separate effects.
PRECONDITIONING ATTENUATES POSTISCHEMIC ADHESION TO RAT MESENTERIC VENULES: ROLE OF R.J. Korthuis, D.C. Gute, T. Akimitsu, and S. Sockrider. Dept LSU Medical Center, Shreveport, LA 71130.
DANAZOL IN THE TREATMENT OF GI HEMORRHAGE SECONDARY TO HEREDITARY HEMORRHAGIC TELANGIECTASIA Yale University School of Medicine, New Haven, CT. Joshua R. Korzenik, Mark Topazian, Catherine Burdge, Robert I.White, Jr.
Ischemic preconditioning (IPC) refers to a phenomenon whereby a tissue is rendered resistant to the deleterious effects of prolonged ischemia and reperfusion (I/R) by prior exposure to very brief period(s) of ischemia. The purposes of this study were to determine whether: (1) IPC would reduce leukocyte adhesion to postcapillary venules in rat mesentery subsequently exposed to a more prolonged period of I/R and (2) adenosine production during the period of preconditioning ischemia contributes to this beneficial effect of IPC on leukocyte adhesion. Methods: Leukocyte adherence (LA) was monitored in single postcapillary venules (20-40 pm diameter) in rat mesentery using intravital video microscopic techniques. After obtaining baseline measurements and video recordings, the small intestine was subjected to 20 min of ischemia followed by 30 min of reperfusion (I/R), with all variables recorded during min 20 to 30 of reperfusion. In a second group of animals, the same protocol was used except that the intestine was subjected to 5 min of ischemia followed by 10 min of reperfusion prior to induction of I/R. To assess the role of adenosine in the beneficial effects of IPC on postischemic LA, the mesentery was superfused with adenosine deaminase (ADA, 0.25 IU/ml superfusate) for 15 min, beginning 5 min before the 5 min period of IPC, and then subjected to I/R. Results: I/R was associated with an increase in leukocyte adhesion (17.8:1:5.5 WBCs/venule) relative to baseline. The postischemic increase in leukocyte adhesion was attenuated by IPC (8.0+1.9 WBCs/venule). I/R was associated with reductions in erythrocyte velocity and venular wall shear rate that were not attenuated by IPC orADA treatment. Thus, the beneficial effect of IPC on LA was not due to elevations in venular wall shear rate. However, superfusion of the mesentery with ADA during the period of preconditioning ischemia completely reversed the protective effects of IPC on LA (21.8+4.2 WBCs/venute), a result which suggests that adenosine plays an important role in the beneficial effects of IPC. Conclusions: Our results indicate that IPC reduces leukocyte adhesion to postcapillary venules in rat small intestine subsequently exposed to a more prolonged period of ischemia and reperfusion. It appears that adenosine produced during the period of preconditioning ischemia plays an important rote in this beneficial effect of IPC. Supported by HL-48646 and DK43785.
Background: Therapeutic options are limited for patients with chronic gastrointestinal bleeding associated with hereditary hemorrhagic telangiectasia (HHT). Local endoscopic treatment has poor efficacy. Systemic therapy has focused almost exclusively on hormonal manipulation with estrogen/progesterone (E/P). Though E/P may benefit up to 70% of these patients, it i s poorly tolerated, contraindicated or frequently refused, particularly by men. A case report suggested dramatic benefit of danazol in a single patient with HHT. Aims: To test the efficacy of danazol in the treatment of chronic GI hemmorrhage due to HHT. Methods Five consecutive patients with HHT who had failed, refused or did not tolerate E/P were treated with danazol (200 mg tid). All were men with an average age of 56.4( range 41-69) and a history of chronic GI bleeding (range 6 months >30 years) despite repeated attempts at endoscopic therapy. Other causes of GI bleeding were excluded. All required at least two units of PRBC (or intravenous iron therapy) in the six months prior to danazol (range 2 - 18 units) Two patients had been previously tried on E/P; one responded but discontinued due to adverse effects. Danazol was considered to have suceeded if a patient maintained his bet without a need for transfusions. Results: Treatment with danazol succeeded in three of the five patients, with excellent responses in less than four weeks. Pt #1:14 units in prior 6 months to 0 units in the subsequent 6 months; pt #2: pre (6 mo ) 2 units, post (6 mo) 0 units with normalization of hemoglobin. Despite an initial response to E/P, pt #3 resumed bleeding after E/P was discontinued due to intolerable adverse effects. His bleeding again resolved on danazol within two weeks. Pt #4 had an equivocal response and danazol was discontinued after 5 months. Pt #5 had no response and was discontinued after one month. Two of these patients (pt # 2 and 3) had minor daily epistaxis which resolved on danazol. Except for transient leg cramps in one patient which resolved on lowering the dose and minor LFF elevations in two patients, no adverse effects were noted. After a sustained response of two months, doses were reduced with continued cessation of bleeding. The positive response to danazol in the three patients has been sustained for 6,7 and 30 months, though the mechanism of its action is uncertain. Conclusion: While larger, randomized triads are required, danazol may offer a much needed alternative therapy for GI bleeding in men with HHT.
Intestinal Disorders
• Effects of chronic arterial hypertension on constitutive and induced ICAM-1 expression in the splanchnic organs. S Komatsu, J Pan6s, MA Perry#, JM Russell, DN Granger Dept. Physiology, LSU Medical Center, Shreveport, LA 71130 #University of South Wales, Sydney, Australia Recent reports indicate that the endothelial cell adhesion molecule, ICAM-1 is upregnlated in response to endotoxin to a greater extent in cultured endothelial cells derived from spontaneously hypertensive (SHR) than cells norrnotensive (WKY) rats. it remains unknown whether such a difference occurs in vivo and whether vessels in splancbnic organs exhibit these altered responses in Chronically hypertensive animals. The objectives of this study were to characterize and compare the in vivo expression of ICAM-1 in SHR and WKY rats, under basal conditions and after exposure to endotoxin. Methods: ICAM-1 expression was studied in the splanchnic organs of untreated or eadotoxin-treated SHR and WKY rats at 5 hours after endotoxin administration (5mg/kg i.p.). ICAM-1 expression was measured using a25Ilabeled anti-rat ICAM-1 mAb (1A29), and an isotype matched control mAb: J3~IP-23 (anti-dog ICAM-1) to correct for nonspecific accumulation of the binding mAb. ICAM-1 corrected activity is expressed as (% injected activity ~25I-1A29./g) - (% injected activity 13~I-P-23Ig), Results: Constitutive expression of ICAM-1 was detected in all splanchnic organs. The levels of constitutive expression of ICAM-1 were similar in SHR and WKY. After endotoxin administration ICAM-1 expression significantly increased in all organs except the liver and spleen in both SHR and WKY rats. However, the magnitude of upregu!ation of ICAM- 1 in both the small and the large intestine was significantly lower in SHR than in WKY (small intestine 0.425-+0.020 vs. 0.527-+0.024 %/g, p<0.01; large intestine 0.317_+0.017 vs. 0.423+0.018 %/g, p<0.01, respectively ). No significant differences hi endotoxin-induced ICAM-1 apregulation were noted between the two groups for fiver, spleen, pancreas~ mesentery, and stomach. Conclusions: Chronic arterial hypertension does not affect constitutive expression of ICAM-1 in splanchnic organs, but is associated with a decreased endotoxin-induced upregnlation of the endothelial cell adhesion molecule in the small and large intestine.(Supported by DK43785)
@ ISCHEMIC LEUKOCYTE ADENOSINE of Physiology,
A297
DISCRIMI ANT EFFECTS OF HEMORRHAGIC SHOCK ON PHAGOCYTIC CLEARANCE AND PHAGOCYTIC KILLING BY THE HEPATIC RETICULOENDOTHELIAL SYSTEM ~ , Dajie Wang, ToshJhiko Ma~am~" Andrew Klein and Gregory Bulkley. Dept of Surgery, the Johns Hopkins University, Baltimore, MD We evaluated the quantitative effects of hemorrhagic shock/r~suscitation (S/R) on two disparate components of hepatic reticuloendothelial system (RES) function in male Sprague Dawley rats. Under pentobarbital anesthesia; rats were subjected to hemorrhagic shock such that mean arterial pressure was maintained at 50-x-5 mmHg for 2h, resuscitated by reinfusion and volume loading for 20m, and then followed for 0, 6 and 24h while the rats developed many components of multiple organ failure syndrome. At the above times, E.coli with cytoplasm labeled with ~lCr and DNA labeled with 12SI-UdRwere injected into the femoral vein and the rats euthanized 90m later. Previous
t''g), ' y ~ p ii (' =.ep "'g nepatlc killing (NHK) reneets me proauct ottlae two:
i0t
8o
8
6 b ~ '
,o
"
y).
J..I 6oq
,
3o
' t4 C 6 ~ t4 time (hI time (h) time (h) S/R significantly decreased HPC at 0 and 6h, but this returned to normal after 24h. On the other hand, HKE was significantly increased at 0 and 24h, but transiently inlfibited at 611. ConSequently, net hepatic killing of blood-borne E.coli was depressed at 0 and 6h, but substanUaUy upregulated al~er 24h. (Even the anesthesia and instrumentation of sham S/R upregulated HKE and consequently net hepatic killing, without affecting HPC.) These findings quantitatively reflect the differential effects of S/K on two different components of hepatic RES function: phagocytic clearance and phagocytic ldlling efficiency. The net effect on net hepatic killing reflects a combination of these two separate effects.
PRECONDITIONING ATTENUATES POSTISCHEMIC ADHESION TO RAT MESENTERIC VENULES: ROLE OF R.J. Korthuis, D.C. Gute, T. Akimitsu, and S. Sockrider. Dept LSU Medical Center, Shreveport, LA 71130.
DANAZOL IN THE TREATMENT OF GI HEMORRHAGE SECONDARY TO HEREDITARY HEMORRHAGIC TELANGIECTASIA Yale University School of Medicine, New Haven, CT. Joshua R. Korzenik, Mark Topazian, Catherine Burdge, Robert I.White, Jr.
Ischemic preconditioning (IPC) refers to a phenomenon whereby a tissue is rendered resistant to the deleterious effects of prolonged ischemia and reperfusion (I/R) by prior exposure to very brief period(s) of ischemia. The purposes of this study were to determine whether: (1) IPC would reduce leukocyte adhesion to postcapillary venules in rat mesentery subsequently exposed to a more prolonged period of I/R and (2) adenosine production during the period of preconditioning ischemia contributes to this beneficial effect of IPC on leukocyte adhesion. Methods: Leukocyte adherence (LA) was monitored in single postcapillary venules (20-40 pm diameter) in rat mesentery using intravital video microscopic techniques. After obtaining baseline measurements and video recordings, the small intestine was subjected to 20 min of ischemia followed by 30 min of reperfusion (I/R), with all variables recorded during min 20 to 30 of reperfusion. In a second group of animals, the same protocol was used except that the intestine was subjected to 5 min of ischemia followed by 10 min of reperfusion prior to induction of I/R. To assess the role of adenosine in the beneficial effects of IPC on postischemic LA, the mesentery was superfused with adenosine deaminase (ADA, 0.25 IU/ml superfusate) for 15 min, beginning 5 min before the 5 min period of IPC, and then subjected to I/R. Results: I/R was associated with an increase in leukocyte adhesion (17.8:1:5.5 WBCs/venule) relative to baseline. The postischemic increase in leukocyte adhesion was attenuated by IPC (8.0+1.9 WBCs/venule). I/R was associated with reductions in erythrocyte velocity and venular wall shear rate that were not attenuated by IPC orADA treatment. Thus, the beneficial effect of IPC on LA was not due to elevations in venular wall shear rate. However, superfusion of the mesentery with ADA during the period of preconditioning ischemia completely reversed the protective effects of IPC on LA (21.8+4.2 WBCs/venute), a result which suggests that adenosine plays an important role in the beneficial effects of IPC. Conclusions: Our results indicate that IPC reduces leukocyte adhesion to postcapillary venules in rat small intestine subsequently exposed to a more prolonged period of ischemia and reperfusion. It appears that adenosine produced during the period of preconditioning ischemia plays an important rote in this beneficial effect of IPC. Supported by HL-48646 and DK43785.
Background: Therapeutic options are limited for patients with chronic gastrointestinal bleeding associated with hereditary hemorrhagic telangiectasia (HHT). Local endoscopic treatment has poor efficacy. Systemic therapy has focused almost exclusively on hormonal manipulation with estrogen/progesterone (E/P). Though E/P may benefit up to 70% of these patients, it i s poorly tolerated, contraindicated or frequently refused, particularly by men. A case report suggested dramatic benefit of danazol in a single patient with HHT. Aims: To test the efficacy of danazol in the treatment of chronic GI hemmorrhage due to HHT. Methods Five consecutive patients with HHT who had failed, refused or did not tolerate E/P were treated with danazol (200 mg tid). All were men with an average age of 56.4( range 41-69) and a history of chronic GI bleeding (range 6 months >30 years) despite repeated attempts at endoscopic therapy. Other causes of GI bleeding were excluded. All required at least two units of PRBC (or intravenous iron therapy) in the six months prior to danazol (range 2 - 18 units) Two patients had been previously tried on E/P; one responded but discontinued due to adverse effects. Danazol was considered to have suceeded if a patient maintained his bet without a need for transfusions. Results: Treatment with danazol succeeded in three of the five patients, with excellent responses in less than four weeks. Pt #1:14 units in prior 6 months to 0 units in the subsequent 6 months; pt #2: pre (6 mo ) 2 units, post (6 mo) 0 units with normalization of hemoglobin. Despite an initial response to E/P, pt #3 resumed bleeding after E/P was discontinued due to intolerable adverse effects. His bleeding again resolved on danazol within two weeks. Pt #4 had an equivocal response and danazol was discontinued after 5 months. Pt #5 had no response and was discontinued after one month. Two of these patients (pt # 2 and 3) had minor daily epistaxis which resolved on danazol. Except for transient leg cramps in one patient which resolved on lowering the dose and minor LFF elevations in two patients, no adverse effects were noted. After a sustained response of two months, doses were reduced with continued cessation of bleeding. The positive response to danazol in the three patients has been sustained for 6,7 and 30 months, though the mechanism of its action is uncertain. Conclusion: While larger, randomized triads are required, danazol may offer a much needed alternative therapy for GI bleeding in men with HHT.