Mesenteric and skeletal muscle microvascular responsiveness in subacute sepsis

This study was performed to assess the effects of subacute sepsis in rats on the in vitro reactivity of arterioles (internal diameter, 100-150 microm) to alpha1- and alpha2-adrenergic stimulation and to angiotensin II. Male Sprague-Dawley rats were rendered septic by intraperitoneal implantation of a gelatin capsule containing sterile rat feces and 1 x 10(6) viable colony forming units of Escherichia coli. Control rats underwent sham laparotomy and implantation of a gelatin capsule containing only sterile feces. In vitro reactivity of arterioles from mesentery and skeletal muscle were studied 48 h later in a pressurized (50 mmHg) no flow state using videomicroscopy. Subacute sepsis decreased the contractile response of nonprecontracted microvessels from both anatomical sites to phenylephrine (both p < .01 versus control) and blunted the relaxation response to staurosporine (both p < .01), an inhibitor of protein kinase C. The small contraction to angiotensin II of mesenteric vessels was inhibited by sepsis (p < .05) but was unaltered in the skeletal muscle microcirculation. In the precontracted mesenteric microvessels from septic rats, endothelium-dependent relaxation to clonidine and to adenosine 5'-diphosphate were decreased (both p < .01 versus control), whereas in skeletal muscle microvessels, clonidine and adenosine 5'-diphosphate elicited constriction (both p < .01). Relaxation to the endothelium independent vasodilators sodium nitroprusside and pinacidil was preserved across all vessels. In conclusion, mesenteric and skeletal muscle microvascular responses to angiotensin II and alpha1- and alpha2-adrenergic stimulation are altered in subacute sepsis. This may in part lead to systemic hypotension and altered organ perfusion during states of chronic sepsis.