Porcine Intestinal Heparin Research Articles

Potentiation of endoperoxide analog-induced platelet aggregation by heparin

The mechanism of heparin-induced platelet aggregation potentiation is much debated. We examined the effects of heparin on platelet aggregation induced by cyclic endoperoxide analog U46,619. Heparin enhanced platelet aggregation in a dose-related fashion. Potentiation of platelet aggregation was also found to be related to the incubation time of heparin and platelet rich plasma. Porcine intestinal heparin and bovine lung heparin exhibited similar patterns. To test the hypothesis of increased platelet thromboxane A 2 production under the influence of heparin, we measured U46,619-induced thromboxane A 2 generation. Heparin was found not to affect platelet thromboxane A 2 generation over a wide range of concentrations. The platelet aggregation potentiating actions of heparin are thus unrelated to thromboxane A 2 pathway.

Anticoagulant activity of heparin octasaccharide.

Porcine intestinal heparin was partially digested with a purified heparinase and an octasaccharide with high-affinity for antithrombin III was isolated from the digest by gel filtration, followed by affinity chromatography on a column of Sepharose 4B coupled with antithrombin III. The anticoagulant activity determined by the activated partial thromboplastin time method of the octasaccharide was 240 units/mg. Fifty percent inactivation activities of the octasaccharide for thrombin and factor Xa in the presence of antithrombin III were 2 and 6.5 times, respectively, higher than those of the initial heparin. These data indicate that the octasaccharide possesses the critical structural integrities required for manifesting these biological activities.

Properties of protease in mast cell granules

A neutral protease partially purified from rat peritoneal mast cells closely resembled α-chymotrypsin in pH optimum and in susceptibility to several inhibitors including chymostatin, but the two enzymes were quite different in some respects. Mast cell protease was a more basic protein than α-chymotrypsin as indicated by their isoelectric points (9.3 and 8.5, respectively). In contrast to α-chymotrypsin, which consisted of three different subunits, mast cell protease was apparently composed of a single polypeptide chain of molecular weight 27,000 as estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. Mast cell heparin ionically linked to mast cell protease and suppressed the activity of the enzyme toward N- benzoyl- l-tyrosine ethyl ester and casein by 35 and 75 per cent, respectively, but it did not affect α-chymotrypsin in a medium containing 50 mM CaCl 2. Porcine intestinal mucosa heparin also showed similar inhibitory effects. The inhibitory action of heparin was more evident in low salt medium. Serotonin (0.25 mM), but not histamine, produced an 80 per cent inhibition of mast cell protease (2 μg) activity toward casein in the presence of heparin (2.5 μg). Zn 2+ (0.008–0.2 mM) also suppressed the protease activity by 40–90 per cent in the presence of heparin.

Stability of Ester Sulfates in Heparin to Solvolysis and Dilute Acid Treatment<xref ref-type="fn" rid="fn1"><sup>1</sup></xref>

The stability of ester sulfates in porcine intestinal heparin to solvolytic desulfation (100 degrees C, 9 H) with dimethylsulfoxide containing 2% pyridine was examined, in comparison with the case of dilute acid treatment (0.1 M HCl, 100 degrees C, 70 min). The resulting heparin modifications were deaminated and the deamination products were fractionated by the procedures reported previously (1978) J. Biochem. 83, 1567-1575). The yields of disulfated disaccharide (b-2) and monosulfated disaccharides (e-2-1 and e-2-3) indicated that 2-O-sulfates in L-iduronic acid residues of heparin were more libile than 6-O-sulfates in glucosamine residues to the dilute acid treatment, whereas the opposite was the case for the solvolysis. The product of heparin modification by solvolysis was similar to whale heparin in the distribution of ester sulfates.

Comparison of bovine lung and porcine intestinal heparin for arterial thrombosis in man

The clinical effectiveness of bovine lung heparin and porcine intestinal heparin for reducing arterial thrombosis was compared in a study of 64 surgical patients (mean age, 63.8 years). Immediately prior to operation, the radial artery was cannulated. The catheters were flushed continuously at a flow rate of 3 ml/hr with 0.9% sodium chloride solution without heparin or with two units per milliliter of either beef lung or pork intestinal mucosa heparin. After 24 hours, arteriography was performed, and vessel diameter and the amount of thrombus present were recorded. The addition of heparin to the flush solution significantly reduced the accumulation of thrombotic material on the surface of intra-arterial cannulae, thus lowering the incidence of clinically detectable arterial occlusion. No significant difference was found in the anticoagulant effectiveness of beef lung-derived heparin as compared with heparin obtained from pork intestinal mucosa.