ALTERATIONS IN BRAIN HEXOKINASE-ACTIVITY ASSOCIATED WITH HEART-FAILURE IN RATS

This study examined the activity of discrete regions of the brain as a ssessed with histological localization and photodensitometric quantifi cation of the metabolic enzyme hexokinase in a group of rats with coro nary occlusion (HF) and in sham-operated control rats. Three weeks aft er surgery, the mean left ventricular end diastolic pressure and right atrial pressure were elevated, and left ventricular peak systolic pre ssure was decreased in the HF group compared with the sham group; thes e findings are also observed during heart failure. In addition, histol ogical data indicated that there was a 37.6 +/- 2.8% outer and 40.8 +/ - 3.1% inner infarct of the myocardium in the group of rats with HF (n = 6). Rats in the control group had no observable damage to the myoca rdium (n = 6). Accompanying these symptoms of heart failure were signi ficant increases in hexokinase activity in the parvocellular (pPVN, 16 .3%) and magnocellular (mPVN, 17.6%) divisions of the paraventricular nucleus of the hypothalamus, and in the locus ceruleus (LC, 17.1%). No changes in hexokinase activity were observed in the median preoptic a rea, supraoptic nucleus (SON), subfornical organ, or posterior hypotha lamus. These results reinforce the idea that heart failure (with coron ary occlusion) is associated with changes in specific areas in the bra in and that metabolic alterations in the pPVN, mPVN, and LC are likely related to alterations in vasopressin production, blood volume regula tion, and sympathoexcitation observed in the heart failure state.