The production of lipolytic activity in rat plasma after the intravenous injection of dextran sulphate

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Abstract
Plasma samples obtained from rats which have been injected with dextran sulfate contain an active lipase. The activity of this enzyme can be measured by the ability of an active plasma sample to clear the turbidity of chyle added to it in vitro. The level of activity induced by the injection of dextran sulfate is directly related to the degree of sulfation of the dextran sulfate molecule. With an increase in the molecular weight of the dextran sulfate injected the level of clearing activity demonstrable in vitro falls. This is at least partly due to the inhibition of the clearing activity by the high-molecular-weight dextran sulfates themselves. An increase in the activity in the plasma, after the injection of such preparations, can be demonstrated in the presence of protamine: it is presumed that the protamine combines with the dextran sulfate and so abolishes its inhibitory effect. The inhibition of clearing activity by the high-molecular-weight dextran sulfates may be due to their interaction with the chyle. The dextran sulfate preparations D 5 and AL, with average molecular weights of 200,000 and 1-2 million respectively, produce clearing activity in rat plasma within 30 sec of their injection. The observation that the clearing activity of a plasma sample is rapidly destroyed at 37[degree] in vitro in the presence of protamine supports the view that the sulfated molecules which induce this activity may also stabilize the enzyme system.