Histamine increases venular permeability via a phospholipase C-NO synthase-guanylate cyclase cascade YUAN YUAN, HARRIS J. GRANGER, DAVID C. ZAWIEJA, DAVID V. DEFILY, AND WILLIAM M. CHILIAN Microcirculation Research Institute and Department of Medical Physiology, Texas A & M University Health Science Center, College Station, Texas 77843-l 114 Yuan, Yuan, Harris J. Granger, David C. Zawieja, David V. DeFily, and William M. Chilian. Histamine in- creases venular permeability via a phospholipase C-NO syn- thase-guanylate cyclase cascade. Am. J. Physiol. 264 (Heart Circ. Physiol. 33): Hl734-H1739, 1993.-In this study, we hy- pothesized that histaminergic increases in venular permeability result from a cascade triggered by activation of phospholipase C (PLC), inducing the synthesis of nitric oxide (NO) and activat- ing guanylate cyclase. The apparent permeability coefficient to albumin (P,) was measured in isolated porcine coronary venules subjected to constant flow and hydrostatic and oncotic pres- sures. Histamine (2.5, 5, and 10 PM) transiently and progres- sively increased Pa. The PLC inhibitor 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC; 100 PM) decreased baseline permeability and abolished the effect of histamine. The NO synthase inhibitor NC:-monomethyl-L-arginine (L-NMMA; 10 PM) and the guanylate cyclase inhibitor 6-anilinoquinoline-5,8- quinone (LY 83583; 10 PM) also blocked the histamine-induced hyperpermeability. L-Arginine (3 mM) reversed the inhibition by L-NMMA. N”-monomethyl-D-arginine did not influence the effect of histamine. Furthermore, sodium nitroprusside (10 PM) augmented P, by two- to threefold; this effect was blocked in the presence of LY 83583 but not altered in the presence of NCDC. The results suggest that histamine increases coronary venular permeability by a direct action on the venular endothelial cells through a PLC-NO synthase-guanylate cyclase-signaling cas- cade. inflammation; coronary microcirculation; apparent permeabil- ity coefficient; soluble guanylate cyclase; guanosine 3’,5’ cyclic monophosphate ENDOGENOUS INFLAMMATORY MEDIATORS, including histamine, are known to increase microvascular perme- ability in a variety of tissues and organs (3, 7, 15, 29, 30, 31). Previous evidence has suggested that two possible intracellular signal transduction pathways are involved in the modulation of permeability by such agonists (1,5, 6, 26,32). One hypothesis involves a calcium-dependent pathway in which agonist binding to the receptors stim- ulates inositol phosphate production, leading to the mo- bilization of intracellular calcium and causing myosin- actin contraction and formation of intercellular gaps (1, 6, 7, 32). The other postulated a calcium-independent pathway involving activation of protein kinase C (PKC) by diacylglycerol (DAG), one of the products of phos- pholipase C (PLC)-catalyzed inositol phospholipid turnover, leading to phosphorylation of the endothelial cytoskeleton and subsequent alterations in endothelial barrier function (5, 6, 10, 12, 13, 20, 26). Although ac- tivation of PLC appears to be important in both cas- cades, the role of PLC in microvascular exchange pro- cesses has not been directly studied, and the relative contribution of each pathway remains unclear. Many permeability-increasing factors, including his- tamine, are also vasodilators that stimulate the synthe- sis of nitric oxide (NO) in vascular endothelial cells (3). Moreover, we previously reported that inhibition of NO production blocked the increase in coronary venular per- meability induced by flow (37), suggesting that NO is involved in the regulation of myocardial solute ex- change. Because stimulation of PLC elevates intracell- ular calcium and the NO synthase is activated by calci- urn-calmodulin (27, 34), we speculated that histamine increases venular permeability through a cascade initi- ated by PLC activation, culminating with NO-stimu- lated guanosine 3’,5’-cyclic monophosphate (cGMP) formation. We tested this hypothesis by directly mea- suring albumin permeability in isolated coronary venules during histaminergic stimulation in the pres- ence of various inhibitors of the enzymes of the pro- posed pathway (PLC, NO synthase, and guanylate cy- clase). To verify that an exogenous donor of NO would produce similar effects to histamine, experiments were also conducted in the presence of sodium nitroprusside (SNP). MATERIALS AND METHODS General Preparation Pigs weighing 9-13 kg were sedated with ketamine (2.5 mg/kg im) and Rompun (2.25 mg/kg im), anesthetized with Nembutal (25 mg/kg iv) and heparinized (250 U/kg iv). After a tracheot- omy and intubation, the animals were ventilated. A left thora- cotomy was performed and the heart was electrically fibrillated, excised, and placed in 4°C physiological saline. The coronary sinus was cannulated, and 3 ml india ink-gelatin-physiological salt solution were infused to clearly define venular microvessels. This solution was prepared by adding 0.2 ml of nondialized india ink (Koh-I-Noor, Bloomsbury, NJ) and 0.35 g of porcine skin gelatin to 10 ml of warm physiological salt solution and filtering through P8 filter paper (Fisher Scientific, Pittsburgh, PA). This perfusate does not affect microvascular endothelial reactivity ( 17). Solutions and Perfusates The albumin-physiological salt solution (APSS) used as a bathing solution while the venules were being dissected had H1734 0363-6135/93 $2.00 Copyright 0 1993 the American Physiological Society