Hyperosmolality, acetate, and lactate: Dilatory factors during peritoneal dialysis

Hyperosmolality, acetate, and lactate: Dilatory factors during peritoneal dialysis. Factors that alter peritoneal blood flow may influence the clearance of solutes during peritoneal dialysis. Arteriolar vasodilation, for instance, could increase the delivery of solutes to the capillaries and venules leading to an increase in solute transport into the peritoneal cavity. This study was designed to identify the vasoactive effects of several major components of McGaw® and Dianeal® peritoneal dialysis solutions to understand how the composition of these solutions may alter in vivo blood flow in the peritoneum. Because the major differences between these solutions and Krebs solution are a high osmolality, a high dextrose concentration, and an acetate or lactate buffer system, we investigated the effects of these components. Rats were anesthetized with a combination of urethane and chloralose. The cremaster muscle, with the nerve and blood supplies from the rat still intact, was placed in a specially designed tissue chamber that was filled with Krebs solutions. A port permitted microscopic observations of the blood vessels. In vivo television microscopy was used to quantitate changes in small arteriole diameters induced by changes in the composition of the solution bathing the cremaster or by the addition of nitroprusside. Hyperosmolality produced by the addition of dextrose, sucrose, or sodium chloride to the Krebs solution induced a submaximal dilation of the small arterioles of the cremaster. The rate of dilation differed depending on the substance used to increase osmolality. A normal osmolality acetate (74mM) or lactate (45mM) solution produced a slow, submaximal dilation of the cremaster arterioles. Hyperosmolar acetate (37 or 74mM) or lactate (45mM) solutions produced a rapid, maximal dilation of these vessels. Because the rate of dilation and maximal effect produced by the commercial dialysis solutions were similar to these same parameters produced by the high-osmolality acetate or lactate solutions, the dilatory effects of McGaw® and Dianeal® solutions appear to be due to the combinations of high osmolality and the buffer anion acetate or lactate. Hyperosmolalite, acetate, et lactate: Facteurs vasodilatateurs au cours de la dialyse peritoneale. Les facteurs qui modifient le debit sanguin peritoneal peuvent influencer la clearance des substances dissoutes au cours de la dialyse peritoneale. La vasodilatation arteriolaire, par exemple, peut augmenter le debit de substances dissoutes aux capillaires et auxveinules, ce qui peut augmenter le transport de substances dissoutes dans la cavite peritoneale. Ce travail a pour but d'identifier les effets vasoactifs de plusieurs constituants importants des solutions de dialyse peritoneale McGaw® et Dianeal® de facon a comprendre comment la composition de ces solutions peut modifier in vivo le debit sanguin dans le peritoine. Puisque les differences majeures entre ces solutions et le Krebs sont une osmolalite elevee, une grande concentration de dextrose et un systeme tampon acetate lactate, nous avons etudie les effects de ces composants. Des rats ont ete anesthesies avec un melange d'urethane et de chloral. Le muscle cremaster avec le nerf et le pedicule vasculaire intacts ont ete places dans une chambre specialement construite et remplie de Krebs. Une fenetre permet l'observation microscopique des vaisseaux. Un systeme de television a ete utilise pour quantifier les modifications des diametres des petites arteres determinees par les changements de composition de la solution baignant le cremaster ou par l'addition de nitroprussiate L'hyperosmo-lalite produite par l'addition de dextrose, sucrose ou chlorure de sodium au determine une dilatation sous-maximale des petites arterioles du cremaster. La vitesse de dilation varie avec la substance utilisee pour determiner l'augmentation d'osmolalite. Une solution d'osmolalite normale d'acetate (74mM) ou de lactate (45mM) produit une dilatation lente, sous-maximale des arterioles du cremaster. Des solutions hyper-osmolaires d'acetate (37 ou 74mM) ou de lactate (45mM) produisent une dilatation rapide et maximale. Puisque la vitesse de dilatation et l'effet maximal produit par les solutions de dialyse du commerce sont semblables a ce qui est obtenu avec des solutions d'acetate ou de lactate d'osmolalite elevee, l'effet vasodilatateur des solutions McGaw® et Dianeal® parait etre du a la combinaison de l'osmolalite elevee et du tampon acetate ou lactate.