Circulating levels of vasoactive peptides in patients with acute bacterial meningitis.
OBJECTIVE
The underlying mechanisms for cerebral blood flow (CBF) abnormalities in acute bacterial meningitis (ABM) are largely unknown. Putative mediators include vasoactive peptides, e.g. calcitonin-gene related peptide (CGRP), vasoactive intestinal peptide (VIP), and endothelin-1 (ET-1), all of which may be affected by therapeutic interventions used in the intensive care unit. We measured arterial levels as well as the net cerebral flux of these peptides in patients with ABM, and in healthy volunteers undergoing interventions relevant to intensive care.


METHODS
Seven patients with severe ABM and sepsis and fifteen healthy volunteers were included after informed consent. The net cerebral fluxes of vasoactive peptides were measured by the Kety-Schmidt technique in ABM patients (baseline study only), as well as in volunteers at baseline, during voluntary hyperventilation, after an intravenous injection of lipopolysaccharide (LPS), and during norepinephrine infusion.


RESULTS
The arterial levels of CGRP, but not of VIP or ET-1, were elevated in patients with ABM, but no net cerebral flux was present. CGRP levels decreased during hyperventilation and after LPS injection. No net cerebral flux of VIP occurred in any group at any time. A cerebral efflux of ET-1, which occurred in volunteers at baseline, was neither present in volunteers after LPS injection nor in patients with ABM.


CONCLUSIONS
The arterial concentration of the vasodilatory peptide, CGRP, but of neither VIP nor the vasoconstrictor ET-1, is elevated in patients with ABM and sepsis. A constitutive cerebral output of ET-1 appears to be present in healthy humans, but is abolished after LPS injection.
Berg
Ronan M G
RM
Department of Infectious Diseases, Centre of Inflammation and Metabolism, University Hospital Rigshospitalet, 2100 Copenhagen, Denmark. ronan@dadlnet.dk
Strauss
Gitte Irene
GI
Tofteng
Flemming
F
Qvist
Tavs
T
Edvinsson
Lars
L
Fahrenkrug
Jan
J
Qvist
Jesper
J
Fonsmark
Lise
L
Skinhøj
Peter
P
Møller
Kirsten
K
D000208:Acute Disease; D000328:Adult; D000368:Aged; D001921:Brain / Q000098:blood supply*; D015740:Calcitonin Gene-Related Peptide / Q000097:blood; D003422:Critical Care; D019332:Endothelin-1; D005260:Female; D006801:Humans; D008070:Lipopolysaccharides / Q000097:blood; D008297:Male; D016920:Meningitis, Bacterial / Q000503:physiopathology*; D008875:Middle Aged; D014660:Vasoactive Intestinal Peptide / Q000097:blood*
D019332:Endothelin-1; D008070:Lipopolysaccharides; D014660:Vasoactive Intestinal Peptide; D015740:Calcitonin Gene-Related Peptide