Skeletal microcirculatory responses to hyperdynamic Escherichia coli sepsis in unanesthetized rats
H. M. Cryer, R. N. Garrison, H. W. Kaebnick, P. D. Harris and L. M. Flint
To determine the microvascular site of vasodilation during hyperdynamic
sepsis, we measured arteriolar and venular responses to live Escherichia
coli bacteremia in the rat cremaster muscle by direct in vivo
videomicroscopy. Our data indicate that cardiac output (by thermodilution)
increased, systemic vascular resistance decreased, and a differential
arteriolar response occurred, with constriction of large arterioles and
dilation of small terminal arterioles. We conclude that dilation of small
terminal arterioles in skeletal muscle could contribute to decreased
systemic vascular resistance during hyperdynamic sepsis. This may be an
appropriate response to increased oxygen demand or decreased tissue
utilization of oxygen. Alternatively, small-arteriole dilation may be an
inappropriate response and secondary to release of vasoactive inflammatory
mediators. If the latter is true, there is a potential therapeutic role for
selective manipulation of the tone of small terminal arterioles in
hyperdynamic sepsis.
