Satoshi Kawahara

Porcine skeletal muscle troponin is a good source of peptides with Angiotensin-I converting enzyme inhibitory activity and antihypertensive effects in spontaneously hypertensive rats.

In the search for novel peptides that inhibit the angiotensin I-converting enzyme (ACE), porcine skeletal troponin was hydrolyzed with pepsin, and the products were subjected to various types of chromatography to isolate active peptides. Glu-Lys-Glu-Arg-Glu-Arg-Gln (EKERERQ) and Lys-Arg-Gln-Lys-Tyr-Asp-Ile (KRQKYDI) were identified as active peptides, and their 50% inhibitory concentrations were found to be 552.5 and 26.2 microM, respectively. These are novel ACE inhibitory peptides, and the activity of KRQKYDI was the strongest among previously reported troponin-originated peptides. KRQKYDI was slowly hydrolyzed by treatment with ACE, and kinetic studies indicated that this peptide was a competitive inhibitor of the enzyme. When KRQKYDI was administered orally to spontaneously hypertensive rats (SHR) at a dose of 10 mg/kg, a temporary antihypertensive activity was observed at 3 and 6 h after administration.

Lipids easy to accumulate in the liver and lipids hard to accumulate in it

Abstract Accumulation of lipids in the liver, fatty acid composition and molecular species of serum and hepatic triglycerides were investigated after rats were raised for 4 weeks with diets containing beef powder and 12% level of various lipids. Some diagnostic parameters in the serum and acetyl-CoA carboxylase and peroxisomal β-oxidation activities of the liver were also examined. The accumulation of lipids in the liver of rats raised with beef tallow and with canola oil was significantly less than that with olive oil. Serum GOT of rats raised with beef tallow was significantly less than that of rats with vegetable oils. Serum GPT was also significantly less in rats with beef tallow than with safflower oil. Fatty acid composition of hepatic lipids was rather dependent on the composition of dietary lipids except in the case of safflower oil. Molecular species of triglycerides of hepatic lipids were quite different from those of dietary lipids, but the difference in the species between serum and hepatic triglycerides were smaller than the difference between dietary and hepatic lipids. Specific activities of acetyl-CoA carboxylase of the liver of rats raised with beef tallow and canola oil were significantly higher than that of rats with safflower oil, while peroxisomal β-oxidation activity of rats with beef tallow showed an intermediate value between olive oil and canola oil.

Is beef tallow really hazardous to health

Effects of dietary lipids combined with meat powder on the concentration of serum triglycerides and cholesterol and on the accumulation of lipids in the liver were investigated. The concentration of serum triglycerides and cholesterol of rats raised with solid fats (palm oil, beef tallow and palm-mid-fraction) were significantly higher than those of rats with soybean oil. However, accumulation of lipids in the liver of rats raised with beef tallow was smaller than that with soybean oil. Fatty acid composition of lipids accumulated in the liver was greatly influenced by the composition of dietary lipids, while the composition of serum lipids was not significantly influenced by dietary lipids.

Changes in expression of the autophagy-related genes MAP1LC3B and ATG7 in skeletal muscle of fattening Japanese Black cattle: a pilot study

Objective Autophagy is a bulk degradation system for intracellular proteins which contributes to skeletal muscle homeostasis, according to previous studies in humans and rodents. However, there is a lack of information on the physiological role of autophagy in the skeletal muscle of meat animals. This study was planned as a pilot study to investigate changes in expression of two major autophagy-related genes, microtubule-associated protein 1 light chain 3β (MAP1LC3B) and autophagy related 7 (ATG7) in fattening beef cattle, and to compare them with skeletal muscle growth. Methods Six castrated Japanese Black cattle (initial body weight: 503±20 kg) were enrolled in this study and fattened for 7 months. Three skeletal muscles, M. longissimus, M. gluteus medius, and M. semimembranosus, were collected by needle biopsy three times during the observation period, and mRNA levels of MAP1LC3B and ATG7 were determined by quantitative reverse-transcription polymerase chain reaction. The expression levels of genes associated with the ubiquitin-proteasome system, another proteolytic mechanism, were also analyzed for comparison with autophagy-related genes. In addition, ultrasonic scanning was repeatedly performed to measure M. longissimus area as an index of muscle growth. Results Our results showed that both MAP1LC3B and ATG7 expression increased over the observation period in all three skeletal muscles. Interestingly, the increase in expression of these two genes in M. longissimus was highly correlated with ultrasonic M. longissimus area and body weight. On the other hand, the expression of genes associated with the ubiquitin-proteasome system was unchanged during the same period. Conclusion These findings suggest that autophagy plays an important role in the growth of skeletal muscle of fattening beef cattle and imply that autophagic activity affects meat productivity.