CORONARY ARTERIOSCLEROSIS IN DOGFISH (SCYLIORHINUS-CANICULA) - AN ASSESSMENT OF SOME POTENTIAL RISK-FACTORS

Coronary myointimal lesions are described in the dogfish (Scyliorhinus canicula). These lesions are similar to those previously described in salmonids and are characterized by breaks in and disappearance of the inner elastic layer and intimal thickening as a result of inclusions of fibers and smooth muscle cells. Lesions are associated with all the branching points in the main subepicardial conal coronary arteries th at supply the heart. Intimal thickenings were rare in other parts of t hese arteries. However, we found extensive lesions unassociated with b ranching points in two main intramyocardial ventricular arteries that supply the ventricular spongy myocardium. We carried out a statistical study of the incidence and severity of these intramyocardial lesions in relation to several potential risk factors. Intimal thickenings wer e present in 90.5% of the fish specimens and 40% of the histological s ections. Sex, reproductive stage, plasma triacylglycerol, and choleste rol (total and related to high-density lipoproteins) were not signific antly related to either the incidence or severity of lesions. Total fi sh length was significantly correlated with the lesion severity index (r=0.33, p<0.01). We also found significant differences in incidence r elated to the location of lesions. The middle areas of the intramyocar dial branches, very close to the atrioventricular canal, were more aff ected than the cranial and caudal areas. The dorsal and ventral artery walls were also more affected than the lateral ones. The preferential location of the lesions in areas presumably subjected to mechanical s tress because of a bifurcating bloodstream or the pulsatile flow throu ghout the atrioventricular canal suggests that coronary arterioscleros is in dogfish is an age-related process, with hemodynamic factors play ing a primary or secondary pathogenetic role. This disease seems not t o be related to some factors suggested for salmonids, such as reproduc tive cycle, anadromous migration, river pollution, or plasma lipid con centration.