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Although endothelin-1 (ET-1)-induced organ hypoperfusion after trauma-hemorrhage is improved by estrogen administration, it remains unclear whether estrogen receptor (ER) subtypes play any role in the attenuation of ET-l-induced vasoconstriction in any specific organ bed. To investigate this, isolated perfusion experiments in the heart, liver, small intestine, kidney, and lung were carried out in sham, at the time of maximum bleedout (MBO; i.e., 5-cm midline incision, with removal of 60% of circulating blood volume over 45 min to maintain a mean blood pressure of 40 mmHg), and 2 h after trauma-hemorrhage and resuscitation (T-H/R). Organ-specific ET-1-induced vasoconstriction was evaluated, and the effects of 17[beta]-estradiol ([E.sub.2]) and ER-specific agonists propylpyrazole triol (PPT; ER[alpha] agonist) and diarylpropionitrile (DPN; ER[beta] agonist) were determined. ET-1 induced the greatest vasoconstriction in sham animals, with the strongest response in the kidneys, followed by the small intestine and liver. ET-1-induced responses were weakest in the heart and lungs. ET-1-induced vasoconstriction was evident at the time of MBO but was significantly decreased at 2 h after T-H/R. ER[beta] plays an important role in cardiac performance, as evidenced by improved heart performance (+ dP/dt) in the presence of DPN. DPN also induced a greater effect than PPT in the reduction of ET-1-induced vasoconstriction in the kidneys and lungs. In contrast, PPT attenuated ET-1-induced vasoconstriction in the liver, whereas both DPN and PPT were equally effective in the small intestine. The increased +dP/dt values induced by [E.sub.2], DPN, or PPT were evident at the time of MBO but were significantly decreased at 2 h after T-H/R. These data indicate that the effects of ET-1 on vasoconstriction and the role of ER subtypes in estrogen-induced vasorelaxation are organ specific and temporally specific after trauma-hemorrhage. maximum bleedout; 17[beta]-estradiol; diarylpropionitrile; propylpyrazole triol

Although endothelin-1 (ET-1) induces vasoconstriction, it remains unknown whether 17[beta]-estradiol ([E.sub.2]) treatment following trauma-hemorrhage alters these ET-1-induced vasoconstrictive effects. In addition, the role of the specific estrogen receptor (ER) subtypes (ER-[alpha] and ER-[beta]) and the endothelium-localized downstream mechanisms of actions of [E.sub.2] remain unclear. We hypothesized that [E.sub.2] attenuates increased ET-1-induced vasoconstriction following trauma-hemorrhage via an ER-[beta]-mediated pathway. To study this, aortic rings were isolated from male SpragueDawley rats following trauma-hemorrhage with or without [E.sub.2] treatment, and alterations in tension were determined in vitro. Doseresponse curves to ET-1 were determined, and the vasoactive properties of [E.sub.2], propylpyrazole triol (PPT, ER-[alpha] agonist), and diarylpropionitrile (DPN, ER-[beta] agonist) were determined. The results showed that trauma-hemorrhage significantly increased ET-1-induced vasoconstriction; however, administration of [E.sub.2] normalized ET-1-induced vasoconstriction in trauma-hemorrhage vessels to the shamoperated control level. The ER-[beta] agonist DPN counteracted ET-1-induced vasoconstriction, whereas the ER-[alpha] agonist PPT was ineffective. Moreover, the vasorelaxing effects of [E.sub.2] were not observed in endothelium-denuded aortic rings or by pretreatment of the tings with a nitric oxide (NO) synthase inhibitor. Cyclooxygenase inhibition with indomethacin had no effect on the action of [E.sub.2]. Thus, [E.sub.2] administration attenuates ET-1-induced vasoconstriction following trauma-hemorrhage via an ER-[beta]-mediated pathway that is dependent on endothelium-derived NO synthesis. estrogen receptor; nitric oxide; endothelium; aortic ring

Although gender differences in intestinal perfusion exist following trauma-hemorrhage (T-H), it remains unknown whether endothelin-1 (ET-1) plays any role in these dimorphic responses. To study this, male, proestrus female (female), and 17[beta]-estradiol (E2)-treated male rats underwent midline laparotomy, hemorrhagic shock (blood pressure 40 mmHg, 90 min), and resuscitation (Ringer lactate, 4x shed blood volume, 1 h). Two hours thereafter, intestinal perfusion flow (IPF) was measured using isolated intestinal perfusion. The IPF in sham-operated males was significantly lower than those in other groups and decreased markedly following T-H. In contrast, no significant decrease in IPF was observed in females and E2 males following T-H. The lower IPF in sham-operated males was significantly elevated by E[T.sub.A] receptor antagonist (BQ-123) administration and was similar to that seen in sham-operated females. The decreased IPF in males after T-H was also attenuated by BQ-123 administration. The intestinal ET-1 levels in sham-operated males were significantly higher than in other groups. Although plasma and intestinal ET-1 levels increased significantly after T-H in all groups, they were highest in males. Plasma E2 levels in females and E2 males were significantly higher than in males; however, they were not affected by T-H. There was a negative correlation between plasma ET-1 and E2 following T-H. Thus ET-1 appears to play an important role in intestinal perfusion failure following T-H in males. Because E2 can modulate this vasoconstrictor effect of ET-1, these findings may partially explain the previously observed salutary effect of estrogen in improving intestinal perfusion following T-H in males. hemorrhagic shock; BQ-123; tissue trauma: 17[beta]-estradiol

Recent studies from our laboratory have shown that alcohol and burn injury impair intestinal barrier and immune functions. Although multiple factors can contribute to impaired intestinal barrier function, such an alteration could result from a decrease in intestinal blood flow (BF) and oxygen delivery (D[O.sub.2]). Therefore, in this study, we tested the hypothesis that alcohol ingestion before burn injury reduces splanchnic blood flow and oxygen delivery. Rats (250 g) were gavaged with alcohol to achieve a blood ethanol level in the range of 100 mg/dl before burn or sham injury (25% total body surface area). Day 1 after injury, animals were anesthetized with methoxyflurane. Blood pressure, cardiac output (CO), [+ or -] dP/dt, organ BF (in ml x [min.sup.-1] x 100 [g.sup.-1]), and D[O.sub.2] (in mg x [ml.sup.-1] x 100 [g.sup.-1]) were determined. CO and organ BF were determined using a radioactive microsphere technique. Our results indicate that blood pressure, CO, and +dP/dt were decreased in rats receiving a combined insult of alcohol and burn injury compared with rats receiving either burn injury or alcohol alone. This is accompanied by a decrease in BF and D[O.sub.2] to the liver and intestine. No significant change in BF to the coronary arteries (heart), brain, lung, skin, and muscles was observed after alcohol and burn injury. In conclusion, the results presented here suggest that alcohol ingestion before burn injury reduces splanchnic BF and D[O.sub.2]. Such decreases in BF and D[O.sub.2] may cause hypoxic insult to the intestine and liver. Although a hypoxic insult to the liver would result in a release of proinflammatory mediators, a similar insult to the intestine will likely perturb both intestinal immune cell and barrier functions, as observed in our previous study. hemodynamic; liver; intestine; shock; trauma; ethanol; cardiovascular response; thermal injury

Although gender differences exist in cardiovascular endothelial function, it remains unclear whether such differences are also seen in small intestinal endothelial function. To determine this, untreated male, age-matched proestrus female, castrated male, and 17[beta]-estradiol (E2)-treated noncastrated male rats were studied. Dose response curves to ACh and nitroglycerin (NTG) were determined by measuring changes in perfusion pressure by using an isolated small intestinal perfusion model. Endothelium-derived nitric oxide (NO) production/release was indirectly determined by the ability of intact endothelium to suppress serotonin ([10.sup.-5] M)-induced perfusion pressure changes. Intestinal tissue levels of NO were also measured. Moreover, plasma levels of androgen and E2 were determined and correlated with ACh ([10.sup.-8] M)-induced perfusion pressure reductions. ACh-induced intestinal perfusion pressure reductions in proestrus females, castrated males, and E2-treated noncastrated males were significantly higher than in untreated males. NTG-induced perfusion pressure reductions were not significantly different among groups. Perfusion pressures after administration of serotonin ([10.sup.-5] M) and intestinal tissue levels of NO in proestrus females, castrated males, and E2-treated noncastrated males were also significantly higher than in untreated males. Plasma androgen levels in proestrus females, castrated males, and in E2-treated noncastrated males were significantly lower compared with untreated males. There was a positive correlation between plasma androgen and ACh-reduced perfusion pressure; however, E2 levels did not show a similar relationship. Thus androgens appear to play an inhibitory role in small intestinal endothelial function. These properties in male vessels can be modulated by decreasing the level of circulating androgens or by E2 treatment. male; female; endothelium; acetylcholine; serotonin; nitroglycerin

Proestrous female rodents are protected from the deleterious effects of trauma-hemorrhage that are observed in males. We hypothesized that the gender dimorphic outcome after trauma-hemorrhage might be related to gender differences in endothelial function and organ perfusion under such conditions. Male and cycle-matched proestrous female Sprague-Dawley rats underwent a midline laparotomy, hemorrhagic shock (40 mmHg for ~90 min), and resuscitation (Ringer lactate, 4x shed blood volume over 60 min). Various parameters were measured 2 h after completion of resuscitation. In the first set of animals, the left ventricle was cannulated and heart performance (maximal rate of left ventricular pressure increase) as well as cardiac output and organ perfusion rates were determined with [sup.85]Sr microspheres. In the second set of animals, aortic vessel rings were harvested and relaxation in response to acetylcholine and nitroglycerin was measured. In the third set of animals, in situ isolated small intestine was perfused to measure the response of the splanchnic vessel bed to acetylcholine and nitroglycerin. After trauma-hemorrhage and resuscitation, females maintained cardiac output and demonstrated increased splanchnic and cardiac perfusion compared with males. Moreover, female intestines did not manifest the endothelial dysfunction that was observed in male intestines after hemorrhagic shock. We conclude that proestrous females show improved endothelial function and tissue perfusion patterns after hemorrhagic shock and that this gender-specific response might be a potential mechanism contributing to the beneficial effects of the proestrus stage under such conditions. cardiac output; endothelial function; coronary artery; gut; liver

Adrenomedullin (AM), a potent vasodilatory peptide, plays an important role in initiating the hyperdynamic response during the early stage of sepsis. Moreover, the reduced vascular responsiveness to AM appears to be responsible for the transition from the early, hyperdynamic to the late, hypodynamic phase of sepsis. Although the novel specific AM binding protein-1 (AMBP-1) enhances AM-mediated action in a cultured cell line, it remains to be determined whether AMBP-1 plays any role in modulating vascular responsiveness to AM during sepsis. To study this, adult male rats were subjected to sepsis by cecal ligation and puncture (CLP). The thoracic aorta was harvested for determination of AM-induced vascular relaxation. Aortic levels of AMBP-1 were determined by Western blot analysis, and AM receptor gene expression in the aortic tissue was assessed by RT-PCR. The results indicate that AMBP-1 significantly enhanced AM-induced vascular relaxation in aortic rings from sham-operated animals. Although vascular responsiveness to AM decreased at 20 h after CLP (i.e., the late, hypodynamic stage of sepsis), addition of AMBP-1 in vitro restored the vascular relaxation induced by AM. Moreover, the aortic level of AMBP-1 decreased significantly at 20 h after CLP. In contrast, AM receptor gene expression was not altered under such conditions. These results, taken together, suggest that AMBP-1 plays an important role in modulating vascular responsiveness to AM, and the reduced AMBP-1 appears to be responsible for the vascular AM hyporesponsiveness observed during the hypodynamic phase of sepsis. vasoactive peptide; complement factor H; adrenomedullin receptors; aorta; vascular relaxation; cecal ligation and puncture

The inactive form of heparin minimizes the damage caused by hemorrhagic shock on cardiovascular and hepatocellular functioning. Rats were bled by laparotomy and reperfused with a solution containing the heparin variant GM1892, which is smaller than naturally-found heparin. GM1892 normalized cardiac output, hepatocellular function and microvascular blood flow after resuscitation. It also minimized morphological changes in the liver, kidney and gut and returned prostaglandin E2 to normal levels.

The ability of nitric oxide to produce a vasodilatory effect on micro and macrocirculation is hindered during sepsis when higher blood flow levels are caused by microbial attack. Sepsis was induced in rats through cecal ligation and puncture, and which were then treated with acetylcholine and nitroglycerin. Only nitroglycerin, which acts independently of nitric oxide derived from the endothelium, was able to relax the aorta and superior mesentery, while acetylcholine did not have a vasodilatory effect five hours after sepsis.

Functioning of depressed endothelial cells upon hemorrhagic shock and resuscitation can be restored by administering ATP-MgCl2. Male Sprague-Dawely rats were used for the experiment. The rats were bled to a mean arterial pressure (MAP)of 40mm Hg within 10 minutes. MAP increased soon after the completion of crystallized resuscitation. ATP-MgCl2 can help protect the cells even without resuscitation.

ATP-MgCl2 treatment normalizes beta-adrenergic receptors and macrophage 3,5,-cyclic monophosphate (cAMP) after trauma-hemorrhage and fluid resuscitation. Both Kupffer cell and peritonial macrophage exhibit a rise in cAMP levels after hemorrhage and resuscitation. ATP-MgCl2 administration significantly reduces the optimum binding capacity of beta-receptor in Kupffer cells and cAMP.

Administration of tumor necrosis factor-alpha (TNF-alpha) enhances plasma-TNF concentration without reducing mean arterial pressure, reduces vascular relaxation of endothelium-derived TNF-alpha and produces depression in endothelium-dependent relaxation by inhibiting NO production through fresh protein synthesis.

Studies on the circulating blood volume (CBV) in rats, following midline laparotomy, reveals that CBV is correlated to hepatocellular dysfunction and may provide a useful estimate of fluid resuscitation following trauma-hemorrhage. The indocyanine green clearance method of CBV levels improves following resuscitation but does not regain control levels.

The effects of hemorrhage on cardiac output (CO) and blood flow (BF) were studied by using the radioactive microsphere technique. Laboratory mice were subjected to laparotomy, bled and maintained at a mean arterial pressure of 35 mmHg for 90 min. Ringer lactate was then used to resuscitate the mice at four times the maximum bleedout. A decrease in CO and BF in organs except the brain and skeletal muscles was observed. The results were then used to develop a reliable trauma-hemorrhage and resuscitation model using the microsphere method.

The small intestine plays an important role in upregulating CGRP during sepsis. Am J Physiol Regulatory Integrative Comp Physiol 280: R382-R388, 2001.--Although studies have indicated that calcitonin gene-related peptide (CGRP), a potent vasodilatory peptide, is upregulated after endotoxic shock, it remains controversial whether this peptide increases during sepsis and, if so, whether the gut is a significant source of CGRP under such conditions. To study this, polymicrobial sepsis was induced by cecal ligation and puncture (CLP) followed by fluid resuscitation. Plasma levels of CGRP were measured at 2, 5, and 10 h after CLP (i.e., early, hyperdynamic sepsis) and at 20 h after CLP (late, hypodynamic sepsis). The results indicate that plasma CGRP did not increase at 2-5 h but increased by 177% at 10 h after CLP (P [is less than] 0.05). At 20 h after the onset of sepsis, however, the elevated plasma CGRP returned to the sham level. To determine the source of the increased plasma CGRP, the liver, spleen, small intestine, lungs, and heart were harvested, and tissue CGRP was assayed at 10 h after CLP in additional animals. Only the small intestine showed a significant increase in tissue levels of CGRP (by 129%, P [is less than] 0.05). Determination of portal vs. systemic levels of CGRP indicates that portal CGRP was 65.7 [+ or -] 22.7% higher than the systemic level at 10 h after CLP, whereas portal CGRP in sham-operated rats was only 4.9 [+ or -] 2.1% higher. Immunohistochemistry examination revealed that CGRP-positive stainings increased in the intestinal tissue but not in the liver at 10 h after the onset of sepsis. The distribution of CGRP stainings was associated with intestinal nerve fibers. These results, taken together, demonstrate that upregulation of CGRP occurs transiently during the progression of sepsis (at the late phase of the hyperdynamic sepsis), and the gut appears to be a major source of such an increase in circulating levels of this peptide. vasoactive peptides; gut; liver; immunohistochemistry; cecal ligation and puncture; hyperdynamic sepsis; calcitonin gene-related peptide

Ba, Zheng F., Ping Wang, Douglas J. Koo, Mian Zhou, William G. Cioffi, Kirby I. Bland, and Irshad H. Chaudry. Testosterone receptor blockade after trauma and hemorrhage attenuates depressed adrenal function. Am J Physiol Regulatory Integrative Comp Physiol 279: R1841-R1848, 2000.--Although the testosterone receptor antagonist flutamide restores the depressed immune function in males after trauma and hemorrhage, it remains unknown whether this agent has any salutary effects on adrenal function. To study this, male rats underwent laparotomy and were bled to and maintained at a blood pressure of 40 mmHg until 40% of the shed blood volume was returned in the form of Ringer lactate. Animals were then resuscitated and fiutamide (25 mg/kg body wt) was administered subcutaneously. Plasma adrenocorticotropic hormone (ACTH) and corticosterone, as well as adrenal corticosterone and cAMP were measured 20 h after resuscitation. In additional animals, ACTH was administered and ACTH-induced corticosterone release and adrenal cAMP were determined. The results indicate that adrenal contents of corticosterone and cAMP were significantly decreased and morphology was altered after hemorrhage. Administration of flutamide improved corticosterone content, restored cAMP content, and attenuated adrenal morphological alterations. Flutamide also improved the diminished ACTH-induced corticosterone release and adrenal cAMP response at 20 h after hemorrhage and resuscitation. Furthermore, the diminished corticosterone response to ACTH stimulation in the isolated adrenal preparation was improved with flutamide. These results suggest that flutamide is a useful adjunct for improving adrenal function in males following trauma and hemorrhage. adrenal function; isolated perfused adrenal preparation; corticosterone; adenosine 3',5'-cycle monophosphate; adrenocorticotropic hormone

Laser-Doppler flowmetry (LDF) is the technique for the measurement of hepatic microcirculatory blood flow (HMBF) that quantifies LDF signals in absolute units of perfusion. A linear correlation exists between laser Doppler flow and organ blood flow calibrations from other techniques. But this physical-optical theoretical model used to calibrate the signal cannot be applied to all tissues. LDF signal quantification can be made more accurate by multiple site sampling and integration into a single LDF output.

Adrenomedullin binding protein-1 modulates vascular responsiveness to adrenomedullin in late sepsis. Am J Physiol Regul Integr Comp Physiol 283: R553-R560, 2002. First published April 11, 2002; 10.1152/ajpregu.00544. 2001.—Adrenomedullin (AM), a potent vasodilatory peptide, plays an important role in initiating the hyperdynamic response during the early stage of sepsis. Moreover, the reduced vascular responsiveness to AM appears to be responsible for the transition from the early, hyperdynamic to the late, hypodynamic phase of sepsis. Although the novel specific AM binding protein-1 (AMBP-1) enhances AM-mediated action in a cultured cell line, it remains to be determined whether AMBP-1 plays any role in modulating vascular responsiveness to AM during sepsis. To study this, adult male rats were subjected to sepsis by cecal ligation and puncture (CLP). The thoracic aorta was harvested for determination of AM-induced vascular relaxation. Aortic levels of AMBP-1 were determined by Western blot analysis, and AM receptor gene expression in the aortic tissue was assessed by RT-PCR. The results indicate that AMBP-1 significantly enhanced AM-induced vascular relaxation in aortic rings from sham-operated animals. Although vascular responsiveness to AM decreased at 20 h after CLP (i.e., the late, hypodynamic stage of sepsis), addition of AMBP-1 in vitro restored the vascular relaxation induced by AM. Moreover, the aortic level of AMBP-1 decreased significantly at 20 h after CLP. In contrast, AM receptor gene expression was not altered under such conditions. These results, taken together, suggest that AMBP-1 plays an important role in modulating vascular responsiveness to AM, and the reduced AMBP-1 appears to be responsible for the vascular AM hyporesponsiveness observed during the hypodynarnic phase of sepsis. [ABSTRACT FROM AUTHOR]