From the Department of Physiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R.lran
Abstract: (4456 Views)
Heart failure is a clinical syndrome characterized by the inability of the heart
to provide nutrient supply to tissues. In 75% of cases, the underlying pathology
causing heart failure in patients with cardiac death is coronary heart disease. A
rabbit model of heart failure with coronary ligation was produced to mimic
coronary heart disease in humans. After producing the model, two arteries and two
veins were investigated in the two groups (control and with coronary ligation).
Arteries and veins were cut as rings and bathed in Krebs solution maintained at 37
DC, and gassed with 95% oxygen and 5% CO
2
, Then all tissues were placed under
different resting tensions and allowed to equilibrate for 1 hour. Then all the tissues
were contracted with U -46619 (0.1 µM) nearly ten minutes before initial application
of isoprenaline. When the U -46619 (0.1 µM)-induced contraction reached a
plateau, concentration-response curves to isoprenaline were obtained. Isoprenaline
was chosen as a vasodilator, it's effect resulting from stimulating beta receptors in
blood vessels. Isoprenaline induced relaxation in all tissues, but the renal artery
was the most sensitive and showed maximum relaxation.20-26 Compared to
acetylcholine, relaxation responses were small and maximum responses observed
in the vena cava, aorta and renal vein were only 10 percent. In all tissues, relaxation
responses to the vasodilator agent isoprenaline showed no significant difference
between control and coronary ligated rabbits 8 weeks after operation.