P. Hsu et al., PROSTANOID SYNTHESIS IN RESPONSE TO HIGH CO2 IN NEWBORN PIG BRAIN MICROVASCULAR ENDOTHELIAL-CELLS, The American journal of physiology, 264(5), 1993, pp. 1485-1492
Hypercapnia-induced cerebral vasodilation involves prostanoids in newb
orn pigs. However, the source of prostanoids has not been determined.
The current study was designed to address the hypothesis that piglet c
erebral microvascular endothelial cells increase their synthesis of pr
ostanoids in response to high CO2. Microvascular endothelial cells, sm
ooth muscle cells, and glia were isolated and grown in primary culture
. They were identified morphologically and by indirect immunofluoresce
nce staining. Cerebral microvascular endothelial cell cultures from ne
wborn pigs produced equal amounts of 6-ketoprostaglandin (PG) F1alpha
(stable hydrolysis product of PGI2) PGE2 and a small amount of PGF2alp
ha under basal conditions. Administration of calcium ionophore A23187
to the endothelial cells increased release of all three prostanoids in
a dose- and time-dependent manner. Exposure of piglet cerebral microv
ascular endothelial cells to higher than normal CO2 increased the prod
uction of 6-keto-PGF1alpha and PGE2 but not of PGF2alpha. The enhanced
prostanoid biosynthesis was concentration dependent, peaking at 14% C
O2, and was detected during the first 10 min exposure to 14% CO2. Hype
rcapnia-induced increased synthesis of prostanoids was blocked dose de
pendently by the simultaneous addition of PGH synthase inhibitor indom
ethacin. High CO2 did not increase prostanoid production by cerebral m
icrovascular smooth muscle cells or glia, although A23187 enhanced pro
stanoid formation by both cell types. These data show that high CO2 st
imulates prostanoid synthesis by newborn pig cerebral microvascular en
dothelial cells, which is consistent with an involvement of cerebral v
ascular endothelium in hypercapnia-induced vasodilation.