The simultaneous effect of albumin bound fatty acids on platelets and endothelial cells

The Role of Platelets in Hypoglycemia-Induced Cardiovascular Disease: A Review of the Literature

Cardiovascular diseases (CVDs) are the leading cause of death globally as well as the leading cause of mortality and morbidity in type 2 diabetes (T2D) patients. Results from large interventional studies have suggested hyperglycemia and poor glycemic control to be largely responsible for the development of CVDs. However, the association between hypoglycemia and cardiovascular events is also a key pathophysiological factor in the development of CVDs. Hypoglycemia is especially prevalent in T2D patients treated with oral sulfonylurea agents or exogenous insulin, increasing the susceptibility of this population to cardiovascular events. The adverse cardiovascular risk of hypoglycemia can persist even after the blood glucose levels have been normalized. Hypoglycemia may lead to vascular disease through mechanisms such as enhanced coagulation, oxidative stress, vascular inflammation, endothelial dysfunction, and platelet activation. In the following review, we summarize the evidence for the role of hypoglycemia in platelet activation and the subsequent effects this may have on the development of CVD. In addition, we review current evidence for the effectiveness of therapies in reducing the risk of CVDs.

The effect of cod liver oil in two populations with low and high intake of dietary fish

Two subgroups of healthy males from an inland and a coastal community in Norway with a traditionally low and high consumption of dietary fish were given a dietary supplement of 20 ml cod liver oil rich in n-3 polyunsaturated fatty acids for 3 weeks. Cod liver oil induced an increase in serum high density lipoprotein (HDL) cholesterol in men from the inland. Both groups showed a prolonged primary bleeding time, whereas platelet aggregation and thromboxane A2 production induced by collagen were mainly unaffected. Platelet phospholipid fatty acids showed similar changes in both groups with a decrease in n-6 and an increase in n-3 polyunsaturated fatty acids. No changes were observed in total cholesterol or platelet phospholipid content. This study shows that dietary supplement with cod liver oil induces changes in serum lipids and platelets that may reduce the tendency to thrombosis both in subjects with a low and in those with a high intake of dietary fish. The effects were more pronounced in the subjects with a traditionally low fish consumption.

Effect of nifedipine monotherapy on platelet aggregation in patients with untreated essential hypertension

The effect of 6 weeks of nifedipine 30-60 mg/d on platelet aggregation and lipid parameters has been studied. A diminution in ADP-, adrenaline- and collagen-induced aggregation was observed. In the case of adrenaline- and collagen-stimulated aggregation the decrease was statistically significant. It was found that platelets which aggregated markedly during the placebo treatment were most strongly inhibited by nifedipine. The changes in lipid parameters were not significantly correlated with changes in aggregation.

Platelet function in classic migraine during attack-free periods

It has been reported that migraine sufferers have an enhanced platelet activity, as well as an enhanced thromboembolic risk. In this study, 12 subjects with classic migraine were compared with 12 age- and sex-matched controls. The following parameters were tested: platelet aggregation; platelet content of ADP, ATP and cyclic-AMP (cAMP); plasma levels of cAMP, 6-keto-PGF1 alpha and thromboxane B2, serum levels of TxB2 and lipids. ADP- and adrenaline-induced platelet aggregation, platelet content of ADP, ATP and cAMP did not differ significantly between the groups. Platelets from migraine subjects, however, showed a decreased beta-adrenoceptor response to stimulation with isoprenaline when determined as platelet cAMP production in vitro. The prostacyclin metabolite 6-keto-PGF 1 alpha was significantly decreased in the migraine group. No difference were observed in TxB2. Plasma lipids were similar, except that the migraine cases had higher levels of LDL-cholesterol. These data do not confirm a general platelet malfunction in migraine patients, but suggest a decreased functional capacity of platelet beta-adrenoceptors and an altered metabolism of prostacyclin and LDL-cholesterol.

Effect of metoprolol and propranolol on platelet aggregation and cAMP level in hypertensive patients

Ten patients with uncomplicated moderate essential hypertension were recruited to evaluate the effect of the non-selective beta-blocker propranolol and the beta 1-selective beta-blocker metoprolol on platelet aggregation and cAMP formation. Five patients began treatment with propranolol 80 mg b.i.d. and 5 with metoprolol 100 mg b.i.d., and after 2 weeks the treatments were exchanged. ADP- and adrenaline-induced platelet aggregation and the basal level of platelet cAMP were measured at the end of each treatment period. Platelet aggregation was tested turbidometrically, using the threshold value for irreversible aggregation, and cAMP measurements were performed using a protein-binding assay. Both ADP and adrenaline threshold values were significantly lower after propranolol than after metoprolol. The basal cAMP level was lower during propranolol than metoprolol treatment. The results indicate that platelet aggregation and basal cAMP level are influenced by beta-blockers in proportion to their affinity to different beta-adrenoceptors. This may be of value in the beta-blocker treatment of patients at high thrombotic risk.

Dihomogammalinolenic acid (20:3 omega 6) is more anti-aggregatory than eicosapentaenoic (20:5 omega 3) in a platelet-endothelial cell mixture

The effect of 20:3 omega 6, the precursor of 1 series prostaglandins was to inhibit platelet aggregation more strongly than either 20:5 omega 3, the precursor of 3 series prostaglandins or 20:3 omega 3 which is not a substrate of prostaglandin synthetase. When platelets and dissociated endothelial cells were pretreated with 20:3 omega 6, platelet aggregation in the presence of endothelial cells was much more inhibited than after 20:5 omega 3 pretreatment.