Diet and Cardiac Arrhythmia: Effects of Lipids on Age-Related Changes in Myocardial Function in the Rat

Abstract

Male rats were fed for 3–4 months (short-term) or 12–15 months (long-term) on a standard laboratory diet alone (control) or supplemented with sunflower seed oil (SSO, 12 % w/w) or sheep kidney fat (SKF, 12% w/w). Papillary muscles were electrically driven (1 Hz, 5 ms, supramaximal voltage) at 37 °C in Krebs-Henseleit solution, and contractions were measured isometrically. Both the positive inotropic responses to CA⁺⁺ and the incidence of spontaneous tachyarrhythmias under catecholamine stress were increased by short-term SKF feeding and with age in control and SKF groups, whereas SSO prevented these changes. The results show a marked effect of age upon ventricular myocardial function in the rat, which appears to be accelerated by the consumption of animal (saturated) fat while polyunsaturated vegetable oil provides some degree of protection. It is suggested that changes in membrane lipid composition can alter the Ca⁺⁺ handling characteristics of myocardial cells.

Influências de dietas ricas em ácidos graxos saturados e insaturados sobre o miocárdio de ratos

“…The lower food consumption in hypercaloric diet rats than controls equalled out caloric intake between the three groups, which resulted in similar final body weights. These data agree with previous experiments using UFA or SFA rich diets [8][9][10][13][14][15] . Analysis of relationships between ventricle weights and rat final body weights showed that animals submitted to SFA diets had biventricular hypertrophy compared to controls, and RV hypertrophy compared to UF animals.…”

“…Although previous studies have shown that diet caused depressed cardiac function depression in isolated rabbit 12 and rat 13 papillary muscle, recent data from our laboratory 15 have shown that, in agreement with other authors 7,9,11,14 , UFA diet does not alter functional performance. On the other hand, there are few reports on the relationship between SFA rich diets and cardiac function.…”

“…While SFA rich foods are atherogenic and reduce coronary reserve 1,3,4 , UFAs have an anti-atherogenic effect 1,5 and protect the heart against the adverse effects of acute phase myocardial infarction 5,6 . Studies on UFA have shown beneficial results in the cardiovascular system 1,5,6 , experiments have shown that diets rich in UFA and SFA cause structural and metabolic damage in the myocardium [6][7][8][9][10] . While both diets cause disorganized sarcolemma, lipid deposits 9,10 , and myocardial oxidative stress 6,10 , the UFA rich diet also promotes necrosis 7 and abnormal muscle striation 8 .…”

“…Studies on UFA have shown beneficial results in the cardiovascular system 1,5,6 , experiments have shown that diets rich in UFA and SFA cause structural and metabolic damage in the myocardium [6][7][8][9][10] . While both diets cause disorganized sarcolemma, lipid deposits 9,10 , and myocardial oxidative stress 6,10 , the UFA rich diet also promotes necrosis 7 and abnormal muscle striation 8 .…”

“…Although literature shows that UFA rich diets cause morphometabolic alterations [6][7][8][9][10] , information is contradictory with respect to their effects on myocardium mechanical function 7,9,[11][12][13][14][15] . Although previous studies have shown that diet caused depressed cardiac function depression in isolated rabbit 12 and rat 13 papillary muscle, recent data from our laboratory 15 have shown that, in agreement with other authors 7,9,11,14 , UFA diet does not alter functional performance.…”