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Arnold/Ruf: The role of polyunsaturated fatty acids for cardiac function

Polyunsaturated fatty acids (PUFAs) are essential dietary components that mammals can not synthesize de novo. PUFAs have profound effects on various physiological processes, such as cardiaovascular function, energy turnover, and body temperature control. Most mammals (both wild and domestic) show seasonal adjustments of these functions, that are associated with seasonal preferences for diets rich in specific PUFAs. Up to now, the molecular pathways by which PUFAs exert their effects are largely unknown, however. We propose that a major pathway by which PUFAs exert their effects in seasonal mammals, is by modulating activity of the Ca⁺⁺ pump (SERCA) in the sarcoplasmatic reticulum of the heart (Ruf & Arnold, 2008). We specifically hypothesize that ω-6 PUFAs stabilize Ca⁺⁺ sequestering in cardiac myocytes of mammals that undergo large fluctuations of body temperature, e.g. hibernators. We will use the Syrian hamster (Mesocricetus auratus), a highly seasonal hibernator, as an animal model to experimentally alter phospholipid composition of tissues via ω-6 PUFA or ω-3 PUFA rich- and reduced diets, and to determine effects of these treatments on cardiac function, SERCA activity  (and SERCA mRNA levels) in the heart during both normothermia and hibernation. Further, we will use body temperature and heart rate telemetry, together with indirect calorimetry, to assess effects of both ω.-6 and ω-3 PUFA phospholipid content on cardiac function, body temperature control, and metabolic rate. This will encompass several sets on experiments over a four year period to investigate (i) long-term seasonal changes and (ii) time courses of SERCA activity and other parameters within hibernation episodes during winter. Because PUFAs are prone to peroxidation and represent a major source of radical oxygen species (ROS), we will also determine markers of oxidative stress to investigate possible trade-offs between the costs and benefits of PUFAs. Further, we will experimentally test increasing evidence that PUFAs can also alter mitochondrial metabolism and respiration in myocytes.

Publication List

1.  Ruf, T; Arnold, W (2008): Effects of polyunsaturated fatty acids on hibernation and torpor: a review and hypothesis. Am J Physiol Regul Integr Comp Physiol (294), 3 R1044-R1052.
2. Valencak, TG; Ruf, T (2007): N-3 polyunsaturated fatty acids impair lifespan but have no role for metabolism. Aging Cell. 2007; 6(1):15-25.
3. Bruns, U; Frey-Roos, F; Pudritz, S; Tataruch, F; Ruf, T; Arnold, W (2000): Essential fatty acids: Their impact on free-living alpine marmots (Marmota marmota). In: Heldmaier, G, Klingenspor, M. editors(s). Life in the cold; 215-222. (ISBN: 3-540-67410-1) pp. 215-222.
4. Bieber, C; Ruf, T (2009): Summer dormancy in edible dormice (Glis glis) without energetic constraints Naturwissenschaften (96), 1 165-171