The hemodynamic effects of acute myocardial ischemia and reperfusion in Clawn miniature pigs

Histopathological background data of the systemic organs of CLAWN miniature swine with coronary artery stent implantation

The aim of this study was to identify potential changes that could occur during histological evaluations of CLAWN miniature swine, with potential consequences for subsequent experiments. The systemic organs from male and female CLAWN miniature swine (16.3–42.3 months old) that had been used in long-term studies of coronary stent implantation were examined histologically. Commonly observed histopathological findings were testicular/epididymal atrophy, cyst-like follicles in the ovaries, hemosiderin deposition in the spleen, lipofuscin deposition in the proximal tubular epithelia and presence of eosinophilic globules in the Bowman’s space and the lumen of the proximal tubules in the kidneys, and cellular infiltration in several organs, including the eyelids, respiratory organs, and digestive tract. However, none of these changes were serious enough to indicate a significant impact on research. In conclusion, this study identified CLAWN miniature swine as a suitable animal model for various experiments.

Microminipig, a non-rodent experimental animal optimized for life science research:novel atherosclerosis model induced by high fat and cholesterol diet

Atherosclerotic lesions were observed in male and ovariectomized female Microminipig (MMP) fed a high fat and cholesterol diet with sodium cholate (HFCD/SC) for 3 months. HFCD/SC induced hypercholesterolemia accompanied by an increase in serum total cholesterol (T-Cho), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and cholesterol ester (CE). Unlike the mouse or rabbit, a dominant LDL-C fraction in the intact MMP, similar to that in humans, was observed by serum lipoprotein analysis. HFCD/SC increased body weight gain. At the end of the experiment, computed tomography scans of conscious animals showed that HFCD/SC had decreased liver attenuation values (Hounsfield unit) and increased subcutaneous and abdominal fat, suggesting the induction of fatty liver and obesity. HFCD/SC induced atherosclerotic lesions in systemic arteries, including the external and internal iliac arteries, abdominal aorta, coronary artery, and cerebral arterial circle. Atherosclerosis and pathological findings induced by HFCD/SC in MMP were similar to those in humans. The MMP is a potentially suitable tool for investigating human atherosclerosis.

Cardiovascular haemodynamics and ventriculo-arterial coupling in an acute pig model of coronary ischaemia-reperfusion

Although reperfusion after coronary occlusion is mandatory for myocardial salvage, reperfusion may trigger a cascade of harmful events (reperfusion injury) adding to myocardial injury. We investigated effects of reperfusion on left ventricular (LV) haemodynamics and ventriculo-arterial (VA) coupling in pigs following acute myocardial ischaemia induced by coronary artery occlusion. Experiments were performed in six animals, with measurements of cardiac and arterial function at baseline, after 60 min of ischaemia (T60) and after 2 (T180) and 4 h of reperfusion (T300). Ventriculo-arterial coupling was assessed using the ventriculo-arterial elastance ratio of paper, as well as using a 'stiffness coupling' and 'temporal coupling' index. Reperfusion following ischaemia (T180 versus T60) induced a progressive decline in cardiovascular function, evidenced by a decrease in mean arterial blood pressure, cardiac output and ejection fraction which was not restored at T300. Although reperfusion also induced an increase in slope of the end-systolic pressure-volume relationship (ESPVR), the ESPVR curve shifted to the right, associated with a depression of contractile function. Histology demonstrated irreversible myocardial damage at T300. The ventriculo-arterial elastance ratio and the 'stiffness coupling' index were unaffected throughout the protocol, but the 'temporal coupling' parameter indicated a relative shift between heart period and the time constant of the arterial system. It is unlikely that these alterations are attributable to ischaemic injury alone. The combination of both the stiffness and temporal coupling index may provide more information when studying ventriculo-arterial coupling than the more commonly used ventricular end-systolic stiffness/effection arterial elastance (E(es)/E(a)) ratio.