Requirement of arteriovenular pairing for increased capillary filtration during acute inflammation.
OBJECTIVE
The purpose of this study was to determine whether the leukocyte chemoattractant N-formyl methionyl-leucyl-phenylalanine (FMLP) increases capillary fluid filtration rate (Jv/S), and if so, to determine whether the mechanism involves arteriovenular communication.


METHODS
Intravital microscopy was used in the rat mesentery to measure capillary Jv/S by a micro-occlusion technique. FMLP was locally superfused through a micropipette near vessels in three different arrangements: 1) near a venule in close pairing with the arteriole feeding the monitored capillary, 2) near an unpaired arteriole feeding the capillary, or 3) near an unpaired venule draining the capillary. In separate experiments, arteriolar hydrostatic pressure (downstream of arteriovenular pairing sites exposed to FMLP) was measured with a micropressure system.


RESULTS
FMLP increased capillary Jv/S when applied to arteriovenular pairing sites, but not when applied to unpaired arterioles or venules. Micropressure measurements in paired arterioles remained essentially constant during FMLP exposure, suggesting that the increase in Jv/S is primarily due to increased capillary permeability.


CONCLUSIONS
With FMLP applied locally to stimulate leukocytes, arteriovenular pairing is required to observe an increase in capillary filtration rate.
Barnidge
J
J
Bioengineering Program, Pennsylvania State University, University Park 16802-6804,USA.
Harris
N R
NR
D000208:Acute Disease; D000818:Animals; D001160:Arterioles / Q000033:anatomy & histology / Q000503:physiopathology*; D001795:Blood Pressure Determination; D002199:Capillary Permeability / Q000187:drug effects* / Q000502:physiology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D007249:Inflammation / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D019410:Interleukin-16 / Q000502:physiology; D008297:Male; D018715:Microscopy, Video; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013152:Splanchnic Circulation / Q000187:drug effects / Q000502:physiology; D014699:Venules / Q000033:anatomy & histology / Q000503:physiopathology*
D019410:Interleukin-16; D009240:N-Formylmethionine Leucyl-Phenylalanine