guanylyl-imidodiphosphate and Sepsis

To study the alteration of Na(+)-Ca2+ exchange in rat cardiac sarcolemmal membrane during phases of septic shock.. Sepsis was induced by cecal ligation and puncture (CLP). Na(+)-Ca2+ exchange was assayed by radioactive analysis.. Na(+)-dependent 45Ca2+ uptake was decreased by 62%-69% in late phase of sepsis, whereas it was not affected in early phase of sepsis. Na(+)-Ca2+ exchange stimulated by 5' guanylyl imidodiphosphate [Gpp (NH) p] was decreased by 65.7% in late phase of sepsis but unaltered in early phase of sepsis. Two agonists (angiotensin II and phenylephrine) coupled to Gq and a protein kinase C activator, phorbol 12-myristate 13-acetate (PMA) all inhibited Na(+)-Ca2+ exchange in late phase of sepsis. Na(+)-Ca2+ exchange activities induced by phosphorylation of Na(+)-Ca2+ exchange were decreased in late phase of sepsis, whereas inhibition of Na(+)-Ca2+ exchange by dephosphorylation was increased both in early and late phases of sepsis.. The alteration of Na(+)-Ca2+ exchange during different phases of sepsis might be related to the activities of Gq, protein kinase C, and phosphorylation/dephosphorylation.

Topics: Animals; Calcium; Guanylyl Imidodiphosphate; Male; Myocardium; Phosphorylation; Rats; Rats, Sprague-Dawley; Sarcolemma; Sepsis; Sodium

Changes in the distribution of (Na+ + K+)-ATPase in two subcellular fractions, the sarcolemma and the light vesicle, of rat heart during sepsis were studied. Sepsis was induced by cecal ligation and puncture (CLP). The alpha-subunit of (Na+ + K+)-ATPase was photoaffinity labeled with [alpha-32P]8-N3ATP. The results show that septic rat heart exhibits hyperdynamic (hypermetabolic) phase during early (9 hr post-CLP), followed by hypodynamic (hypometabolic) phase during late (18 hr post-CLP) sepsis. Marker enzyme and beta-adrenergic receptor assays depict that the light vesicle fraction is the intracellular site of surface receptor. The incorporation of the photolabel into the alpha-subunit (M(r) = 98,000) of the (Na+ + K+)-ATPase in sarcolemmal fraction was increased by 60% (P < 0.01) during early sepsis, but was decreased by 63% (P < 0.01) during late sepsis. In contrast, the binding of 98,000-M(r) peptide in light vesicles was decreased by 40% (P < 0.01) in early sepsis, but was increased by 102% (P < 0.01) during late sepsis. The ouabain-sensitive (Na+ + K+)-ATPase activity was increased by 31% (P < 0.05) during the early sepsis, but was decreased by 32% (P < 0.01) during late sepsis in the sarcolemmal fraction; while in the light vesicle fraction, the (Na+ + K+)-ATPase activity was decreased by 21% (P < 0.01) during early sepsis, but was increased by 47% (P < 0.01) during the late phase of sepsis. The yield of membrane proteins for each specific fraction remained unchanged for control, early sepsis, and late sepsis.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Affinity Labels; Animals; Azides; Binding, Competitive; Dihydroalprenolol; Guanylyl Imidodiphosphate; Isoproterenol; Male; Myocardium; Ouabain; Photochemistry; Rats; Rats, Sprague-Dawley; Receptors, Adrenergic, beta; Sarcolemma; Sepsis