Catecholamine-induced cardiovascular disease in the spontaneously hypertensive and atherosclerotic turkey

The interest evoked by the Broad Breasted White Turkey (BBWT) as an animal model for studying the cardiovascular damages produced by hypertension and catecholamines is mainly due to the fact that hypertension is spontaneous and tissue and circulating catecholamines, especially norepinephrine, are extremely high. In this paper we focused our attention on three characteristic pathophysiological features displayed by these animals which are strictly related, as well as in humans, to the elevated blood pressure values and to catecholamine action. We also described the possibility of modifying the development of some of these lesions with pharmacological interventions liable to antagonize the peripheral effects of norepinephrine and epinephrine. The dissecting aneurysm of the aorta accounts for 5-10% of sudden deaths in this animal strain. It can be prevented by lowering blood pressure, especially with beta-blockers, and facilitated by MAO-inhibitors. The degree of cardiac hypertrophy is remarkably high and unexpectedly characterized by the synthesis of a "fast" V1-like isomyosin with high Ca++ activated ATPase activity, oxygen consumption and speed of muscle shortening. Neither the reduction of the degree of cardiac hypertrophy, nor treatment with labetalol alone were able to modify this peculiar pattern. In spite of having very high levels of high-density-lipoproteins, which are known to be protective against atherosclerosis, this animal develops a severe atheromatous disease especially in the abdominal aorta, where the cellular growth has also been proven to be in vitro more pronounced than in the thoracic tract. Treatment with beta-blockers reduced the severity and extent of the lesion even in absence of a significant reduction in blood pressure.