Abstract
Administration of exogenous sulfidopeptide leukotrienes (LTs) is associated with enhanced microvascular permeability. In addition, endogenous LTs have been implicated as participants in permeability (nonhydrostatic) edema formation. The source of LTs for interaction with the microvasculature is, however, unknown. We hypothesized that pericytes contribute to vascular LT synthesis. Under basal conditions and after incubation with either the calcium ionophore, A23187 (0-1 μM), or arachidonic acid (20 μM), bovine retinal pericytes (BRPs) did not produce significant amounts of sulfidopeptide LTs. In contrast, in the presence of polymorphonuclear leukocytes (PMNs), which can synthesize LTA4, but not sulfidopeptide leukotrienes, incubation of BRPs with A23187 resulted in dose-dependent increases in LTC4/D4/E4 production (peak: 35.4 ± 5 pg/μg protein; n = 12). Similarly, BRPs, incubated with exogenous, authentic LTA4 (10 μM), synthesized sulfidopeptide LTs (peak: 18.9 ± 5 pg/μg protein,n = 3). Preincubation (30 min) of BRPs with PMNs and the lipoxygenase inhibitor, esculetin (1 × 10−4 M; n = 12), reduced peak A23187-induced production of LTs by 63.9 ± 7%. Finally, Northern blot analysis revealed mRNA for 5-lipoxygenase to be present in human and bovine PMNs, but not in BRPs. These results suggest that pericytes produce sulfidopeptide LTs only when provided with LTA4 from an external source such as the PMN. Interactions between pericytes and PMNs may lead to the production of sulfidopeptide LTs, which, in turn, could alter microvascular permeability.
Footnotes
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Send reprint requests to: Dr. Andrew J. Lonigro, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104.
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↵1 This study was supported by an American Heart Association Grant (Missouri Affiliate) and by National Institutes of Health (NHLBI) Grants HL51298 and HL52675.
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↵2 Current address: University of Glasgow, Division of Neuroscience and Life Sciences, Institute of Biomedical and Life Sciences, West Medical Building, Glasgow G12 8 QQ, UK.
- Abbreviations:
- LT
- leukotriene
- BRP
- bovine retinal pericyte
- PMN
- polymorphonuclear leukocyte
- PG
- prostaglandin
- PBS
- phosphate-buffered saline
- MEM
- modified Eagle’s medium
- BCA
- bicinchoninic acid
- BSA
- bovine serum albumin
- EIA
- enzyme-linked immunoassay
- DMSO
- dimethylsulfoxide
- Received December 3, 1997.
- Accepted February 16, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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