Resistance exercise acutely enhances mesenteric artery insulin-induced relaxation in healthy rats

AIMS

We evaluated the mechanisms involved in insulin-induced vasodilatation after acute resistance exercise in healthy rats.

MAIN METHODS

Wistar rats were divided into 3 groups: control (CT), electrically stimulated (ES) and resistance exercise (RE). Immediately after acute RE (15 sets with 10 repetitions at 70% of maximal intensity), the animals were sacrificed and rings of mesenteric artery were mounted in an isometric system. After this, concentration-response curves to insulin were performed in control condition and in the presence of LY294002 (PI3K inhibitor), L-NAME (NOS inhibitor), L-NAME+TEA (K(+) channels inhibitor), LY294002+BQ123 (ET-A antagonist) or ouabain (Na(+)/K(+) ATPase inhibitor).

KEY FINDINGS

Acute RE increased insulin-induced vasorelaxation as compared to control (CT: Rmax=7.3 ± 0.4% and RE: Rmax=15.8 ± 0.8%; p<0.001). NOS inhibition reduced (p<0.001) this vasorelaxation from both groups (CT: Rmax=2.0 ± 0.3%, and RE: Rmax=-1.2 ± 0.1%), while PI3K inhibition abolished the vasorelaxation in CT (Rmax=-0.1±0.3%, p<0.001), and caused vasoconstriction in RE (Rmax=-6.5 ± 0.6%). That insulin-induced vasoconstriction on PI3K inhibition was abolished (p<0.001) by the ET-A antagonist (Rmax=2.9 ± 0.4%). Additionally, acute RE enhanced (p<0.001) the functional activity of the ouabain-sensitive Na(+)/K(+) ATPase activity (Rmax=10.7 ± 0.4%) and of the K(+) channels (Rmax=-6.1±0.5%; p<0.001) in the insulin-induced vasorelaxation as compared to CT.

SIGNIFICANCE

Such results suggest that acute RE promotes enhanced insulin-induced vasodilatation, which could act as a fine tuning to vascular tone.

Biogenic amine formation in turkey meat under modified atmosphere packaging with extended shelf life: Index of freshness

The aim of this study was to evaluate the effect of modified atmosphere packaging (MAP) on biogenic amine production in turkey meat according to its shelf life period, determining an index of freshness. Sliced meat samples of different meat quality categories (according to color and pH₂₄) were individually packaged under aerobiosis (aerobic package) and in 6 different modified atmospheres containing different gas mixtures: MAP1, 50% N₂/50% CO₂; MAP2, 0.5% CO/50% CO₂/49.5% N₂; MAP3, 50% Ar/50% N₂; MAP4, 0.5% CO/80% CO₂/19.5% N₂; MAP5, 100% N₂; and MAP6, 50% Ar/50% CO₂. All samples were stored at 0 ± 1°C in the dark for between 12 and 25 d. Meat samples packaged in aerobic packaging were analyzed for their microbial and physicochemical characteristics on d 0, 5, and 12 of storage, and then extended to 19 and 25 d when samples were under MAP. The production of biogenic amines analyzed in turkey meat increased over time. The values of putrescine, cadaverine, and tyramine increased significantly (P < 0.05) during storage time in samples packaged under aerobiosis, MAP3, and MAP5. Histamine was not detected in turkey meat packaged under study conditions, or when present, the levels were below the limit of quantification (1.03 mg/kg). Tyramine in turkey meat under MAP was not the best amine indicator of meat deterioration, with cadaverine being suggested instead, or the sum of the amines putrescine, cadaverine, and tyramine, to characterize and quantify meat freshness. After 25 d of storage, the meat packaged under MAP with a mixture containing a higher concentration of CO₂ and with CO was the one with a lower index value (11.36 mg/kg), although not significantly different from the indices provided by the meat packaged with MAP1, 2, and 6.

Antibiotic resistance and virulence factors among Enterococci isolated from chouriço, a traditional Portuguese dry fermented sausage

Enterococci are ubiquitous microorganisms, found as part of the normal intestinal microbiota of many animals. They can be present in food products, for example, the Portuguese dry fermented sausage chouriço. Twenty enterococci were isolated from chouriço in two processing units; after identification and typification by conventional-molecular methods, the isolates were screened for virulence factors and antibiotic resistance. Identification allocated all enterococci to the species Enterococcus faecalis, and PCR fingerprinting demonstrated that each isolate was specific to the processing unit and chouriço from which it was recovered. Regarding the screening for virulence factors, 1 strain produced cytolysin and 4 were gelatinase positive, but none produced lipase. The ace gene was detected in 1 enterococci, ebpABC and efaA(fs) in 16 isolates each, esp in 3, fsrB in 5, gelE in 7, and cylA in 1. A multiresistant phenotype was observed in 8 isolates, 6 belonging to factory A. The antibiotic resistance gene ere(B) was detected in 9 enterococci, whereas the genes tet(M), aac(6')-Ie-aph(2''), and vanA were detected in 8 isolates each. As some of the E. faecalis chouriço isolates present a multiresistant profile and harbor virulence and/or resistance genes, to assess further the safety of Portuguese dry sausages, a larger number of products and processing units must by analyzed.

Incidence of pectoralis major turkey muscles with light and dark color in a Portuguese slaughterhouse

Turkey meat and processed products are very popular in Portugal. However, no studies have been made to assess turkey meat quality. The main objective of this study was to evaluate the quality of turkey breast meat in a Portuguese slaughterhouse, differentiating it to obtain better industrial management, performance, and consumer contentment. Nine hundred and seventy-seven male turkeys (from 16 to 20 wk old) from different flocks (BUT 9 and BIG 6) were evaluated to assess meat quality. Turkeys were slaughtered on different days, electrically stunned (225 V/3 s), and scalded in a vertical water bath at 81 degrees C/5 min. On the slaughter line, the pH and temperature were measured on the pectoralis muscle 15 min postmortem. The carcasses were fast-cooled in a tunnel (-2 degrees C/2 m.s(-1)/90% RH) for 2 h and kept in a refrigeration chamber (0 degree C/85% RH) until deboning (approximately 24 h postmortem). Color and pH 24 h postmortem (pH(24)) were measured on the pectoralis major muscle after carcass deboning. Pectoralis major muscles were selected according to criteria used by Barbut (1996) and drip loss, cooking loss, and total pigments analysis were performed on 67 different sliced meat samples. Muscles classified by pH decline rate, called rapid glycolytic, did not present final quality characteristics that could relate them with pale, soft, and exudative- (PSE) like meat, because there was no relationship between pH 15 h postmortem and lightness (L*), drip loss, or cooking loss. The differences, founded on physicochemical characteristics within pectoralis major muscles, allowed us to establish a criteria of turkey meat quality for dark and PSE-like meat, with L* < or = 44 and pH(24) > or = 5.8 and L* > or = 50 and pH(24) < 5.8, respectively. Based on criteria, the studied population presented 8.1% of carcasses with PSE-like muscles and 12.1% with dark muscles. The association of pH(24) and L* as criteria classification can be useful to classify turkey meat quality.

Gastrointestinal parasites and prey items from a mass stranding of false killer whales, Pseudorca crassidens, in Rio Grande do Sul, Southern Brazil

The gastrointestinal tract of 14 false killer whales, 6 males and 8 females, stranded in June 1995 in southern Brazil, with total standard lengths from 338 to 507 cm, were analysed for endoparasites and food items. A pregnant female had a male foetus of 77.5 cm. Parasites were found in all 14 false killer whales. The nematode Anisakis simplex (Rudolphi, 1809) was found in the stomach of 57% of the animals and the acanthocephalan Bolbosoma capitatum (Linstow, 1889) Porta, 1908 was present in the intestine of all specimens and showed densities up to 600 m-1. An unidentified cestode (Tethrabothridae) was found also in the intestines of 14% of the individuals. The high infections of B. capitatum and A. simplex were not directly related with the cause of death. In the stomachs of four females, beaks of at least eight specimens of the oceanic and epipelagic species Ommastrephes bartramii (Lesueur, 1821) were found, with mantle lengths ranging from 189.8 to 360.9 mm. The distribution of O. bartramii in the coast of Rio Grande do Sul is consistent with false killer whales feeding in continental shelf waters.