EFFECTS OF ANGIOTENSIN-II, NOREPINEPHRINE, AND WALL STRESS ON PROTEIN-SYNTHESIS INDUCTION AND C-MYC EXPRESSION IN RAT HEARTS WITH PRESSURE-OVERLOAD HYPERTROPHY

SCHUNKERT, H and BRUCKSCHLEGEL, G and HOLMER, SR and SCHNEIDER, M and HUBER, G and RIEGGER, GAJ and LORELL, BH (1994) EFFECTS OF ANGIOTENSIN-II, NOREPINEPHRINE, AND WALL STRESS ON PROTEIN-SYNTHESIS INDUCTION AND C-MYC EXPRESSION IN RAT HEARTS WITH PRESSURE-OVERLOAD HYPERTROPHY. NIEREN-UND HOCHDRUCKKRANKHEITEN, 23 (4). pp. 141-143. ISSN 0300-5224,

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Abstract

The effects of growth promoting stimuli on cardiac protein synthesis and c-myc mRNA expression were studied in isolated perfused rat hearts with chronic left ventricular pressure overload (8 weeks banding of the ascending aorta, LVH) and sham operated controls. New protein synthesis (incorporation of H-3-phenylalanine [Phe]) and c-myc mRNA levels (Northern blot) were analysed after a 3-hour perfusion protocol. Under baseline conditions, Phe-incorporation (250 nmoles/gram protein/h) and c-myc mRNA levels were similar in control (n = 6) and LVH hearts (n = 5). In control hearts, infusion of angiotensin II (AII; 10(-8) M plus prazosin 10(-7) M; n = 6) or norepinephrine (Nor, 10(-6) M, n = 5) were related to 2 4-fold (AII, p < 0.001) and 2-fold (Nor, p < 0.05) induction of Phe-incorporation in both left and right ventricles. In contrast, perfusion of LVH-hearts resulted in small (AII: 1.5-fold; n = 6; p = NS) or no (Nor; n = 5) induction of cardiac protein synthesis that was significantly lower than in respective control groups (p < 0.005 and p < 0.05). Imposition of cardiac load (100 mmHg/g LV, n = 5) increased Phe-incorporation 1.7-fold (p < 0.05) and c-myc mRNA levels 3-fold (p <0.05) in the stressed left ventricles of control hearts. Stimulation of LVH-hearts with identical wall stress resulted in a blunted induction of both Phe-incorporation and c-myc mRNA. In summary, the data suggest that in contrast to baseline metabolism acute induction of protein synthesis by neurohumoral or mechanical stimulation may be altered in hearts with established LVH.

Item Type: Article
Uncontrolled Keywords: ; ANGIOTENSIN-II; NOREPINEPHRINE; PROTEIN SYNTHESIS; C-MYC; LEFT VENTRICULAR HYPERTROPHY
Depositing User: Dr. Gernot Deinzer
Last Modified: 19 Oct 2022 08:40
URI: https://pred.uni-regensburg.de/id/eprint/53383

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