Expression of anaphylatoxin receptors on platelets in patients with coronary heart disease.

OBJECTIVE: Inhibition of components of the complement system or of its receptors has been postulated as a concept for primary and secondary prevention in atherosclerosis and was applied in clinical trials. Although the anaphylatoxin-receptors C3aR and C5aR are commonly associated with inflammatory cells, in vitro studies suggested their expression also on platelets. METHODS AND RESULTS: Expression levels of C3aR and C5aR were measured by flow cytometry in a collective of 302 patients with documented coronary artery disease (CAD) including patients with stable CAD (n = 152), unstable angina (n = 54), acute myocardial infarction (AMI; Non-ST elevation myocardial infarction, n = 70, ST elevation MI, n = 26) or healthy controls (n = 21). Patients with stable CAD, unstable angina or AMI had significantly higher expression of C5aR on platelets in comparison to healthy controls (MFI 14.68 (5.2), 14.56 (5.18) and 13.34 (4.52) versus 10.68 (3.1)); p < 0.001). In contrast, the expression of C3aR on platelets was significantly enhanced in patients with stable and unstable CAD but not in patients with AMI compared to controls. While there was a strong correlation between the soluble ligands of these receptors C3a and C5a, we observed only a weak correlation with their receptors on platelets. Similarly, agonist induced aggregation (MEA, ADP, and TRAP) showed only a weak correlation with the expression level of anaphylatoxin - receptors on platelets. Of note, the expression of both anaphylatoxin-receptors on platelets strongly correlated with platelet activation as assessed with the surface activation marker P-selectin (r = 0.47, p > 0.001 for C3aR, r = 0.76 for C5aR, p < 0.001). Likewise, we observed a positive correlation of C3aR with other molecules associated with platelet activation such as SDF-1. CONCLUSION: In summary, we observed a positive correlation between the expression of anaphylatoxin-receptors C3aR and C5aR with platelet activation in patients with CAD. Further investigations are needed to study the clinical and mechanistic relevance of these findings.

Effect of dietary linoleic acid and essential fatty acid deficiency on resting metabolism, nonshivering thermogenesis and brown adipose tissue in the rat.

Rats were fed a diet either deficient (0.05%) in essential fatty acids (EFA), or providing 4% (control) and 10% (surplus) of the total energy intake in the form of linoleic acid. All diets were isoenergetic and provided 13.9% of the energy as fat. The rats were kept at 29 or 5 degrees C. Growth and food intake of rats fed linoleic acid surplus at either temperature for 10 wk were not different from that of controls; basal metabolism, norepinephrine-induced nonshivering thermogenesis (NST) and thermogenic variables in the brown adipose tissue (amount of mitochondria and mitochondrial uncoupling protein) also were not different. The effects of EFA deficiency were drastically enhanced in the cold: After 10 wk of consuming a diet low in EFA at 5 degrees C, the body weight of rats was 75% of that of controls (87% at 29 degrees C); the food intake was 135% of controls at 5 degrees C (120% at 29 degrees C). The resting respiration in deficient rats was 125% of controls at 5 degrees C (110% at 29 degrees C); body temperatures as low as 35.1 degrees C were measured in deficient rats after 3 wk at 5 degrees C; the cold tolerance of the rats was significantly diminished (30% died within 3 wk at 5 degrees C), thus emphasizing the essential role of dietary EFA during cold stress. Norepinephrine-induced NST and the thermogenic parameters in brown fat were not influenced by EFA deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding of diltiazem and verapamil to isolated rat heart mitochondria.

The occurrence of arrhythmias was studied in the "calcium-paradox" model in the isolated rat heart. Clear relationships were found between the duration of calcium-free perfusion and (a) the occurrence of calcium-free-induced electrophysiological changes, (b) the incidence and duration of subsequently induced calcium-repletion arrhythmias and (c) mechanical recovery at the end of the repletion period. The first signs of electrophysiological changes (i.e. decreased heart rate, T-wave amplitude and increased PQ-interval) and irreversible loss of myocardial recovery occurred during or after 60-90 s of calcium-free perfusion. The occurrence of calcium-repletion induced ventricular tachycardia paralleled this onset of irreversible cardiac injury. These results suggest that the process of calcium washout and subsequent sudden calcium overloading may play a role as a trigger in the pathogenesis of ventricular arrhythmias.

The effect of essential fatty acid deficiency on basal respiration and function of liver mitochondria in rats.

Rats were fed a diet poor (0.05%) in essential fatty acids (EFA) with hydrogenated coconut oil as fat component, or a control diet containing 4% of the total energy intake in the form of linoleic acid. Effects of dietary EFA deficiency were investigated during a period of 2-30 weeks. Growth retardation becomes significant after 4 weeks of deficiency and attains about 25% when the deficiency is maintained for longer than 12 weeks. Respiration, body weight and age of EFA-deficient rats and controls are in a nonlinear relationship. Basal respiration in relation to the body weight is significantly increased by EFA deficiency; it is unchanged when related to total animals under the employed experimental conditions. Oxidative phosphorylation in isolated liver mitochondria is unaffected by EFA deficiency, i.e., the increased metabolic rate of EFA-deficient rats, related to the body weight, cannot be explained from impaired functional integrity of the inner mitochondrial membrane. Respiratory chain enzyme activities in mitochondria from heart and skeletal muscle and specific amounts of mitochondria in these tissues are unchanged by EFA deficiency.