ABSTRACT
This study investigates the hypothesis that the elevation of intracellular cAMP may affect cytokine-induced expression of adhesion molecules on human vascular smooth muscle cells. In cultured human smooth muscle cells from coronary arteries and saphenous veins, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) induced the expression of intercellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule (VCAM-1), whereas interferon-gamma (INF-gamma) selectively stimulated the expression of ICAM-1. Adenylyl cyclase was stimulated either by the stable prostacyclin mimetic cicaprost or by forskolin. Adhesion molecules were detected by a cell surface enzyme immunoassay and the respective mRNA by reverse transcriptase polymerase chain reaction (rt-PCR). Cicaprost as well as forskolin significantly inhibited TNF-alpha- and IL-1 beta-induced cell surface expression of ICAM-1 and VCAM-1. Semiquantitative rt-PCR measurements showed a marked decrease of TNF-alpha- and IL-1 beta-induced mRNA levels of both adhesion molecules after preincubation with cicaprost. The stability of TNF-alpha-induced ICAM-1 and VCAM-1 expression at mRNA and protein level was not altered by cicaprost. The IFN-gamma-induced increase of cell surface expression of ICAM-1 and the respective mRNA levels, however, were not significantly altered by elevation of intracellular cAMP. Basal and stimulated cAMP levels, measured by radioimmunoassay, did not differ in TNF-alpha- and IFN gamma-treated cells. The present results demonstrate that the expression of adhesion molecules on human smooth muscle cells induced by cytokines is differentially modulated by activation of adenylyl cyclase.
Subject(s)
Cyclic AMP/physiology , Intercellular Adhesion Molecule-1/biosynthesis , Interleukin-1/pharmacology , Muscle, Smooth, Vascular/drug effects , Second Messenger Systems/physiology , Tumor Necrosis Factor-alpha/pharmacology , Vascular Cell Adhesion Molecule-1/biosynthesis , 1-Methyl-3-isobutylxanthine/pharmacology , Adenylyl Cyclases/metabolism , Bucladesine/pharmacology , Cells, Cultured , Colforsin/pharmacology , Coronary Vessels/cytology , Coronary Vessels/drug effects , Enzyme Activation/drug effects , Epoprostenol/analogs & derivatives , Epoprostenol/pharmacology , Humans , Intercellular Adhesion Molecule-1/genetics , Interferon-gamma/pharmacology , Muscle, Smooth, Vascular/metabolism , Organ Specificity , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Recombinant Proteins/pharmacology , Saphenous Vein/cytology , Saphenous Vein/drug effects , Vascular Cell Adhesion Molecule-1/geneticsABSTRACT
The objective of this study was to determine whether or not a relationship exists between free fatty acid (FFA) extraction by skeletal muscle and onset of irreversible shock. Hind limb skeletal muscle vasculature of anesthetized dogs was surgically isolated from cutaneous tissue and subjected to a modified Wigger's hemorrhage shock protocol which was divided into five stages (I-V). Since the first signs of irreversibility began in stage II, this stage of hypovolemic hypotension was subdivided into IIa, IIb and IIc. Arterial and venous blood samples were taken during each stage for subsequent blood gas and FFA analysis. The data indicated that the onset of severe tissue ischemia and metabolic acidosis occurs concurrently with increased uptake of FFA and skeletal muscle vasodilation (decompensation). A possible physiological explanation for these observations could be related to an increased synthesis and release of PGE1. This agent has been shown by others to inhibit adrenergic neurotransmitter release causing loss of vascular tone.
