Non-pharmacological modification of cardiac risk factors: part 3. Smoking cessation and alcohol consumption

Smoking cessation (SC) is probably the single most important risk factor modification for both primary and secondary prevention of cardiovascular disease. Interventions to stop smoking are highly cost effective. SC produces reductions in mortality and morbidity that generally outweigh any increase in risk due to weight gain, unless the gain is so great that it is accompanied by adverse changes in blood pressure, lipid profile or glucose tolerance. There is clear evidence that SC improves the lipid profile, decreases thrombotic tendency, reduces vascular endothelial damage and improves insulin sensitivity. Epidemiological studies consistently demonstrate a reduced risk of developing coronary heart disease (CHD) with moderate alcohol consumption (showing protection at < or = 2 drinks per day), but an increased risk at higher alcohol consumption levels. Potential mediators of these cardioprotective effects include an increase in high-density cholesterol (HDL-C), decreased clotting propensity, enhanced insulin sensitivity and glucose tolerance, and a possible lowering of blood pressure at low consumption levels in women. Alcohol consumption may not, however, compensate for the large increase in risk produced by smoking. Whereas moderate alcohol consumption slightly reduces the risk of death between the ages of 35 and 69 years, cigarette smoking approximately doubles the risk.

The effects of combined treatment with beta 1-selective receptor antagonists and lipid-lowering drugs on fat metabolism and measures of fatigue during moderate intensity exercise: a placebo-controlled study in healthy subjects

AIMS

We examined the effects of different combinations of beta 1-selective adrenoceptor blockers and lipid-lowering drugs, on fat metabolism and fatigue during moderate intensity exercise in 14 healthy young volunteers.

METHODS

The study was a randomized crossover design, each subject completing 5, 90 min walks at 50% of predetermined maximal oxygen uptake (VO2 max), one following each 3 day treatment period with either: atenolol 100 mg and bezafibrate 400 mg, atenolol 100 mg and fluvastatin 40 mg, metoprolol CR 100 mg and bezafibrate 400 mg, metoprolol CR 100 mg and fluvastatin 40 mg, or placebo.

RESULTS

Plasma free fatty acid (FFA) concentration during exercise was significantly reduced on all treatments, in comparison with placebo, P = 0.0001. Following 90 min of exercise FFA levels were as follows: placebo 573 mumol l-1 (105-1041), metoprolol CR + fluvastatin 277 mumol l-1 (0-647), metoprolol CR + bezafibrate 182 mumol l-1 (0-396), atenolol + fluvastatin 211 mumol l-1 (0-511), and atenolol + bezafibrate 123 mumol l-1 (0-352). Total fat oxidation during exercise was also reduced on all treatments in comparison with placebo: 38.1% (2-74), compared with 29.1% (0-61) on metoprolol CR + fluvastatin, P = 0.02, 26.2% (2-51) on metoprolol CR + bezafibrate, P = 0.002, 25.5% (3-48) on atenolol + fluvastatin, P = 0.009, and 22.8% (0-47) on atenolol + bezafibrate treatment, P = 0.0002. Plasma ammonia concentration was elevated on all treatments during exercise in comparison with placebo. After 90 min of exercise, plasma ammonia levels were as follows: placebo 37 mumol l-1 (0-84), metoprolol CR + fluvastatin 56 mumol l-1 (2-110), metoprolol CR + bezafibrate 79 mumol l-1 (0-167), atenolol + fluvastatin 90 mumol l-1 (10-170), and atenolol + bezafibrate 100 mumol l-1 26-174). In comparison with placebo, metoprolol CR + fluvastatin had the least adverse impact on measures of perceived exertion and the 'feeling scale' during exercise. Metoprolol CR + bezafibrate, atenolol + fluvastatin, and atenolol + bezafibrate treatments had greater adverse effects, particularly on perceived 'cardiorespiratory effort' and 'feeling scale' scores.

CONCLUSIONS

In healthy volunteers, combinations of beta 1-selective blockers and lipid-lowering drugs were associated with significant reductions in fat metabolism, increased plasma ammonia levels, and raised the perception of effort during exercise, in comparison with placebo. Metoprolol CR + fluvastatin had the least effect, combinations metoprolol CR + bezafibrate and atenolol + fluvastatin had intermediate effects, and atenolol + bezafibrate had the most adverse effect.

Non-pharmacological modification of cardiac risk factors: Part 1

Many factors influence whether a person will develop coronary heart disease. Genetic predisposition, gender and advanced age are recognized risk factors for the development of coronary heart disease over which we have little control. On the other hand, high serum cholesterol, cigarette smoking, high blood pressure, excessive body weight and long-term physical inactivity are key risk factors over which we have considerable control. In many cases cardiac risk factors can be modified without resorting to pharmacological intervention. Current evidence suggests that individuals who follow a diet which is low in saturated fats and cholesterol, lose weight, stop cigarette smoking and take regular aerobic exercise will significantly reduce their risk of developing coronary heart disease. In addition, patients who already have evidence of coronary heart disease may improve their symptoms and prognosis by similar life-style changes. In the first of two parts, we review the role of exercise in modifying cardiac risk factors.

A comparison of the effects of fluvastatin and bezafibrate on exercise metabolism: a placebo-controlled study in healthy normolipidaemic subjects

1. We have examined the interaction between aerobic exercise and lipid-lowering drugs in a crossover study of 16 healthy normolipidaemic volunteers who each received 21 days' treatment with bezafibrate (400 mg), fluvastatin (40 mg), and placebo, in random order. 2. Fluvastatin treatment reduced pre-exercise total cholesterol (TC) by 23% (P < 0.0001), low-density lipoprotein cholesterol (LDL-C) by 33% (P < 0.0001), and plasma triglycerides by 11%, compared with pre-treatment values. Bezafibrate reduced TC by 11% (P < 0.01); LDL-C by 9%; and plasma triglycerides by 40% (P < 0.01), compared with pre-treatment values. 3. During exercise, in comparison with placebo, and fluvastatin treatment, respectively, bezafibrate significantly reduced mean fat oxidation: 31% vs 39%, P = 0.035, 31% vs 39%, P = 0.002, plasma free fatty acid (FFA) availability, e.g. after 90 min of exercise: (t90) 520 vs 662 mumol 1(-1), P = 0.054, 520 vs 725 mumol 1(-1), P = 0.016, and plasma levels of glycerol (t90): 59 vs 74 mumol 1(-1), P = 0.037, 59 vs 73 mumol 1(-1), P = 0.016. Fluvastatin had no impact on fat metabolism in comparison with placebo. 4. Reduced plasma FFA concentration and lower fat oxidation during prolonged exercise on bezafibrate treatment may be due to an inhibition of hepatic acetyl coenzyme A carboxylase, resulting in reduced FFA release from adipose tissue. 5. The possibility that impaired fat metabolism on fibrates could induce premature fatigue during exercise of moderate duration and intensity should be examined in hyperlipidaemic patients.

In vivo measurement of liver perfusion in the normal and partially hepatectomized rat using Tc-99m sulfur colloid

A nonsacrificial technique for measurement of liver perfusion in rats using Tc-99m sulfur colloid and gamma camera with computer system is described. The results of measurement in normal rats and at various stages after partial hepatectomy are presented and are compared with results obtained by workers using other techniques. The method reported here is simpler to perform than those previously reported and has the additional advantage that frequent sequential determinations of liver perfusion can be made.