Mark G. Clemens

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Heme oxygenase (HO)-1 is up-regulated after ischemia/reperfusion and contributes to maintenance of hepatic perfusion and integrity. Blockade of HO-1 leads to an increased portal pressor response in the stress-exposed liver. We tested whether the increase in portal pressure reflects unmasking of a concomitant up-regulation of the vasoconstrictor endothelin(More)
During recent years, increasing experimental evidence has suggested that hepatic nonparenchymal cells, in particular Kupffer cells and neutrophils, can contribute significantly to the pathogenesis of liver injury in various chemical toxicities. Neutrophils are central to the mechanism of injury after hepatic ischemia reperfusion and endotoxemia. In this(More)
Heme oxygenase (HO) catalyzes the oxidative cleavage of the alpha-mesocarbon of Fe-protoporphyrin-IX yielding equimolar amounts of biliverdin-IXa, iron, and carbon monoxide. The HO-system consists of two isoenzymes, namely HO-2 and the inducible isoform HO-1, also referred to as heat shock protein (hsp) 32. Although both parenchymal and non-parenchymal(More)
Heme oxygenase (HO)-derived carbon monoxide (CO) may contribute to vascular control through elevation of guanosine 3',5'-cyclic monophosphate. In the present study, we investigated the functional significance of expression of the isoenzyme HO-1 (heat-shock protein 32) in liver after hemorrhage/resuscitation (H/R) in rats anesthetized with pentobarbital(More)
We conducted this study to elucidate the role of endothelins (ET-1) in mediating the hepatic microcirculatory dysfunction observed in response to sepsis. Following 24 h of cecal ligation and puncture (CLP), we performed intravital microscopy both in vivo and on isolated perfused livers. Portal resistance increased in response to ET-1 in both sham and septic(More)
The rat is increasingly being used to study the physiological response to elevated intra-abdominal pressure (IAP) during laparoscopic surgery. Although decreased portal venous flow associated with the elevated IAP has been reported in large animals, little information is available in rats. Furthermore, the relative blood flow changes in the hepatic artery(More)
Gap junctional cellular communication is important in the propagation of signals that coordinate hepatic metabolism. Hepatocytes express two different connexin (Cx) genes, Cx32 and Cx26, which encode for the subunit component of gap junction channels. Previous studies have shown that the expression of hepatic Cx32 is reduced during inflammatory conditions.(More)
Considerable attention has recently been focused on the phenomenon of active constriction of sinusoids as a mechanisms for regulating perfusion of the liver. Although many methods for estimating liver blood flow have been used in the past, the ability to directly study vascular responses in the sinusoids required the spatial and temporal resolution provided(More)
In this study we investigated whether a low-dose infusion of ATP-MgCl2 could ameliorate the pulmonary hypertension resulting from hypoxic pulmonary vasoconstriction. Three-week-old piglets were anesthetized, intubated, ventilated with room air, and cannulated for the measurement of pulmonary and systemic arterial pressure and pulmonary artery flow (cardiac(More)