Halothane-sensitive Pigs Research Articles

Can pale, soft, exudative pork be prevented by postmortem sodium bicarbonate injection?

Previous attempts at eliminating the problem of PSE pork by genetic selection or rapid postmortem cooling have been only partially successful. A new approach, namely, postmortem injection of sodium bicarbonate (SBC), was tested on halothane-positive gilts. Sixteen pigs were used to establish a suitable SBC concentration. At approximately 15 min after death, the longissimus of one side of the carcass was injected with 10% (by weight) of .2 to .4 M SBC solutions containing .7% NaCl (wt/vol). All concentrations resulted in a higher ultimate pH, improved muscle color, and reduced drip loss. In a second experiment, with 23 pigs, .3 M SBC was injected into the longissimus and the biceps femoris at either 15 min or 24 h after death and with or without inclusion of .7% NaCl (wt/vol). Compared with controls, the 15-min SBC + NaCl injected samples had darker color (L* of 47 vs 53 in controls), higher ultimate pH (5.6 vs 5.3), lower drip loss (5% vs 10%), and increased protein solubility (140 vs 115 mg/g). Injection at 24 h reduced drip loss (from 10% to 5.7%) but did not correct the color defect. The SBC alone and SBC + NaCl treatments had essentially the same effects in reducing drip loss, increasing ultimate pH, and improving color; but the SBC-NaCl injected samples had improved juiciness and flavor compared with SBC. Early postmortem sodium bicarbonate injection seems to prevent the development of PSE pork when injected into carcasses of halothane-sensitive pigs.

In vivo muscle 31P nuclear magnetic resonance spectroscopy during treatment of halothane-sensitive and halothane-nonsensitive pigs

Summary In vivo muscle 31P nuclear magnetic resonance spectroscopy was performed on 10 female pigs originating from a homozygous halothane-sensitive line and on 10 female pigs from a homozygous halothane-nonsensitive line. The mean concentration of phosphocreatine in the biceps femoris muscle of the anesthetized pigs decreased to 86% of the initial value after 11 minutes of halothane exposure (3%, oxygen flow 3 L/min). After the next 5.6 minutes, phosphocreatine concentration reached a minimal value of 52%, followed by a mean recovery to 76% of the initial value during the ensuing 11 minutes. Response was not observed in anesthetized homozygous halothane-nonsensitive pigs. Thus, a decrease to 86% of the initial value of phosphocreatine was 100% predictive for homozygous halothane-sensitive pigs with body weight ranging from 10 to 18 kg.

Halothane genotype by weight interactions on pig meat quality

The effects of slaughter weight on pork quality as influenced by halothane genotype and breed (Lacombe: LAC, NN-genotype; Yorkshire: YRK, NN-genotype) were investigated in 312 carcasses ranging in weight from less than 65 kg to greater than 105 kg. When adjusted to a warm carcass weight of 87 kg, the longissimus of LAC pigs has normal color and structure scores (2.96 and 2.99, respectively), while halothane-sensitive pigs (HSL, nn-genotype) and XBD (HSL × LAC, Nn-genotype) pigs had inferior color (2.69 and 2.83) and structure (2.55 and 2.74) scores on a 5-point scale with 3 being desirable. The results were corroborated with objective measurements of meat quality including expressible juice, drip, protein solubility and muscle color. At lighter carcass weights (65–75 kg), XBD pigs had pork quality characteristics similar to those of LAC pigs, while at heavier carcass weights (95–105 kg) pork quality from these pigs more closely resembled those of the HSL pigs. Subjective pork color and structure scoring of 85-kg YRK and LAC carcasses suggested they were normal and equivalent to each other. However, objective evaluation of pork quality found that YRK carcasses had 15 g kg −1 greater expressible juice, 8 g kg−1 greater drip and 7 g kg−1 less soluble protein than LAC carcasses, indicating meat from YRK carcasses would have lower processing yields than meat from LAC carcasses. LAC carcasses had 6 kg kg−1 greater intramuscular fat on a wet-matter basis than YRK. These results suggest that the dominance of the halothane gene as it affects pork quality may increase with increasing slaughter weight, and LAC pigs produce higher quality pork than YRK pigs. Key words: Meat quality, market weight, genotype, halothane gene, Lacombe, Yorkshire

Halothane genotype by weight interactions on lean yield from pork carcasses

Data on 42 halothane-sensitive pigs (HSL, nn-genotype), 169 Lacombe pigs (LAC, NN-genotype), 41 crossbred pigs (XBD, Nn-genotype), and 72 Yorkshire pigs (YRK, NN-genotype) representing 145 gilts and 179 castrates, were obtained over the liveweight range from 74.0 to 134.5 kg (average 105 kg) to examine the effect of genotype, gender and slaughter weight on the composition of the four lean cuts (ham, loin, picnic and butt). Gilts had a greater proportion of dissectible lean from lean cuts than castrates (557 ± 2.8 vs. 525 ± 2.6 g kg−1). The HSL pigs had the highest and LAC pigs the lowest commercial dressing percentage, increasing respectively from 85.3 to 86.0% and 79.7 kg to 82.6% as slaughter weight increased from 80 to 130 kg. Corresponding figures for XBD and YRK pigs, were 82.5 to 85.4 and 80.6 to 84.6%, respectively. Dissectible lean from lean cuts from 65-kg carcasses was 606, 525, 536 and 575 g kg−1 for HSL, XBD, LAC and YRK pigs, respectively. Corresponding figures for 85-kg and 105-kg carcasses were 574, 525, 515, and 555 g kg−1 and 542, 525, 494, and 535 g kg−1, respectively from HSL, XBD, LAC and YRK pigs. LAC and YRK pigs, each with exclusively NN-genotypes but differing in composition of lean cuts, maintained their relative differences in composition over the weight range studied. Heterogeneity of slopes for changes in proportion of lean in the lean cuts with increasing weight among the HSL, XBD and LAC pigs implied a genotype × weight interaction that could best by explained by an apparent increase in the dominance of the halothane gene with increasing carcass weight. Key words: Swine, carcass composition, halothane gene, weight, Lacombe, Yorkshire

Mitochondrial nucleotide translocase from skeletal muscle of halothane sensitive pigs: An electrophoretic study

ATP translocation into mitochondria isolated from halothane-sensitive pig (HP) muscle was dramatically reduced compared with normal pigs (NP). To determine if this was due to a decreased amount of ATP translocase in the mitochondrial membranes, or a structural modification of this protein, an electrophoretic study was undertaken. Total proteins and purified translocase preparations from (NP) and (HP) mitochondria were analyzed by SDS gel electrophoresis. In the two types of mitochondria no significant differences were observed either in the amount of ATP translocase or in the molecular weight. Also, neither nonequilibrium pH gradient gel electrophoresis nor the analysis of peptides produced by limited proteolysis revealed any structural difference between the two types of protein. On the basis of these results, the depressed translocase activity observed in (HP) mitochondria cannot be explained by a reduced amount of the nucleotide translocase, nor a structural alteration of this protein. Possible inhibition of (HP) translocase activity by Ca2+ accumulation or by other mechanisms is discussed.

Ryanodine receptor gene is a candidate for predisposition to malignant hyperthermia

Malignant hyperthermia (MH) is a potentially lethal condition in which sustained muscle contracture, with attendant hypercatabolic reactions and elevation in body temperature, are triggered by commonly used inhalational anaesthetics and skeletal muscle relaxants. In humans, the trait is usually inherited in an autosomal dominant fashion, but in halothane-sensitive pigs with a similar phenotype, inheritance of the disease is autosomal recessive or co-dominant. A simple and accurate non-invasive test for the gene is not available and predisposition to the disease is currently determined through a halothane- and/or caffeine-induced contracture test on a skeletal muscle biopsy. Because Ca2+ is the chief regulator of muscle contraction and metabolism, the primary defect in MH is believed to lie in Ca2+ regulation. Indeed, several studies indicate a defect in the Ca2+ release channel of the sarcoplasmic reticulum, making it a prime candidate for the altered gene product in predisposed individuals. We have recently cloned complementary DNA and genomic DNA encoding the human ryanodine receptor (the Ca2(+)-release channel of the sarcoplasmic reticulum) and mapped the ryanodine receptor gene (RYR) to region q13.1 of human chromosome 19 (ref. 14), in close proximity to genetic markers that have been shown to map near the MH susceptibility locus in humans and the halothane-sensitive gene in pigs. As a more definitive test of whether the RYR gene is a candidate gene for the human MH phenotype, we have carried out a linkage study with MH families to determine whether the MH phenotype segregates with chromosome 19q markers, including markers in the RYR gene. Co-segregation of MH with RYR markers, resulting in a lod score of 4.20 at a linkage distance of zero centimorgans, indicates that MH is likely to be caused by mutations in the RYR gene.

Halothane-sensitivity gene and muscle contractile properties in malignant hyperthermia.

Malignant hyperthermia (MH) results from the presence of the halothane-sensitivity gene and is characterized by abnormalities in muscle function. Populations of genetically defined pigs were used to determine the in vivo and in vitro expression of this gene in both the homozygous and the heterozygous condition. On exposure to halothane, isolated muscle bundles from the homozygous halothane-sensitive pigs exhibited decreased tetanus tension and increased tetanus half-relaxation time and contracture and were clearly distinguished from homozygous normal muscles. The heterozygous and homozygous normal muscles were similar in contractile responses except for the occurrence of halothane-induced contractures in the heterozygotes. The heterozygous halothane-negative pigs did not exhibit the characteristic signs of an MH episode in response to halothane succinylcholine, although some metabolic responses were significantly altered (e.g., increased venous partial pressure of CO2 and arterial and venous K+ concentration). Thus the heterozygous pigs were not MH susceptible but did represent a phenotype distinct from the homozygous normal pigs both in vitro and in vivo. These data provide the first convincing evidence for the expression of the halothane-sensitivity gene in heterozygotes.

Effects of the halothane-sensitivity gene on sarcoplasmic reticulum function.

Pigs heterozygous for the halothane-sensitivity gene exhibit a distinct phenotype with regard to both in vivo and in vitro muscle responses to halothane (E. M. Gallant, J. R. Mickelson, B. D. Roggow, S. K. Donaldson, C. F. Louis, and W. E. Rempel. Am. J. Physiol. 257 (Cell Physiol. 26): C781-C786, 1989). In this paper heavy sarcoplasmic reticulum (SR) preparations were isolated from the muscles of pigs of all three genotypes. The rate of calcium release from SR of pigs homozygous for the halothane-sensitivity gene was approximately twice that of SR from pigs homozygous for the normal allele. Furthermore, in the presence of 6 microM Ca2+, the binding of [3H]ryanodine to SR isolated from the homozygous halothane-sensitive pigs was of a higher affinity than was the binding to SR isolated from the homozygous normal pigs (Kd = 70-90 vs. 265 nM, respectively). The SR from pigs heterozygous for the halothane-sensitivity gene, however, demonstrated intermediate values for the rate of calcium release and the affinity for [3H]ryanodine (Kd = 192 nM). Thus the alterations in heavy SR calcium release and [3H]ryanodine binding in the pigs containing one copy of the halothane-sensitivity gene demonstrate a distinct heterozygote phenotype. These data also suggest that the protein product of this gene is closely associated with, and perhaps identical to, the SR calcium release channel-ryanodine receptor protein.

THE DEVELOPMENT OF A HALOTHANE-SENSITIVE LINE OF PIGS

A halothane-sensitive line of pigs was developed from a Pietrain-Lacombe synthetic line through selection of breeding stock based on their sensitivity to a 4 min, 4.5% halothane challenge. It appears that halothane sensitivity is inherited by a single, autosomal recessive allele (n), that is essentially fully penetrant (0.98) in halothane-sensitive pigs (nn). The gene was fixed within four cycles of selection. Segregation at the halothane locus among the two sexes provided no evidence to suggest differential mortality between the sexes and fit inheritance patterns typical of an autosomal locus. However, litters that originated from nn × nn mating types had 1.3 fewer pigs weaned per litter than those mating types in which at least one parent carried the halothane gene. There was no evidence for any expression of halothane sensitivity in normal pigs (NN) and only infrequent expression in the heterozygote (Nn). Key words: Halothane gene, inheritance, swine

Cardiac Manifestation and Blood Catecholamine Levels during Succinylcholine‐Induced Stress of Malignant Hyperthermia Sensitive Pigs*

Fifteen crossbred pigs of Swedish Landrace and Yorkshire, about 6 months of age and susceptible to develop malignant hyperthermia (MH) when exposed to halothane, were subjected to stress provoked by the myorelaxant succinylcholine. The results were compared with those of 12 normal pigs. During the stress the halothane-sensitive (HS) pigs showed much higher levels of plasma noradrenaline and adrenaline and more severe ventricular arrhythmias than the controls. The degree of myocardial degeneration and necrosis being similar to catecholamine induced myocardial damage was significantly higher in the HS pigs than in the controls. The ultrastructural examination revealed three main types of changes in affected myocardial cells. One type of myocardial cell damage was characterized by various degree of hypercontraction, enlarged mitochondria with dense bodies and dilated sarcoplasmic reticulum. The other type showed mitochondria with tubular configuration whereas the third type of cell damage was characterized by almost normal mitochondria combined with a severe damage of the myofilaments. Three HS pigs which died within 30 min after stress showed signs of malignant hyperthermia. No signs of the disease were observed in the other 12 HS pigs.

Phospholipase A 2 activity, calmodulin, Ca 2+ and meat quality in young and adult halothane-sensitive and halothane-insensitive British Landrace pigs

PSE (pale, soft and exudative) meat is the result of a developmental disorder and is not produced in meat from young (3–11 weeks) halothane-sensitive British Landrace pigs. Formation of the PSE condition is closely associated with the muscle mitochondrial phospholipase A 2 activity, which increases significantly from 12 weeks of age. The increase in phospholipase A 2 activity shows good correlation (r = 0·87) with the increase in post-mortem sarcoplasmic Ca 2+. In halothane-insensitive British Landrace both the phospholipase A 2 activity and sarcoplasmic Ca 2+ level remain constant throughout growth. Significant increases in the levels of endogenous mitochondrial calmodulin, fatty acids and phospholipase A 2 activity, and Ca 2+ (mitochondrial and sarcoplasmic) are observed in the M. longissimus dorsi of adult halothane-sensitive pigs when compared with either young halothane-sensitive or young and adult halothane-insensitive pigs. The enhanced mitochondrial phospholipase A 2 activity is calmodulin-dependent and the increase in activity is postulated to be due to increased endogenous calmodulin.

Gene order and recombination rates in the linkage group S-Phi-Hal-H-(Po2)-Pgd in pigs.

Families of Czech Landrace (94 litters and 636 offspring) were tested for halothane sensitivity, A-O (S), H, PHI and PGD phenotypes. Informative matings for the estimation of recombination rates between marker loci were selected. The following recombination frequencies were established: S - Phi = 4.8% (2.5%-10.7%); S - H = 6.8% (4.3%-11.7%); Phi - H = 2.6% (0.9%-5.3%); H - Pgd = 4.4% (1.6%-8.0%). Cross-overs were observed also between S - Hal, Hal - H and Hal - Pgd, but were not found between Phi - Hal. On the basis of these results it has been possible to revise the position of the S locus in this linkage group. The most probable gene order would be: S - Phi - Hal (or Hal - Phi) - H - (Po2) - Pgd. A striking difference was found between the number of halothane-sensitive pigs (87) and HalnHaln genotypes determined by haplotyping (123). Segregation rates in 19 backcross matings and experimental matings of the animals proved that this difference is mostly due to incomplete penetrance or low expression of halothane sensitivity.

Comparison of halothane-sensitive and halothane-resistant litter-mate pigs for growth, carcass composition, hormonal status and energy balance

In three experiments with a total of 116 Belgian Landrace pigs, the differences between halothane-sensitive (HS) and halothane-resistant (HR) litter-mates were investigated with respect to growth performance, carcass composition, serum level of insulin and thyroid hormones and energy balance. In ad libitum feeding conditions (Experiment 1), HR pigs ate 9% more than HS pigs, and had a higher growth rate but a fatter carcass. By diluting the ration for the HR pigs, with cellulose (Experiment 2), the differences disappeared, since the HR pigs did not compensate by a higher intake on this bulky ration. In Experiment 3, the pigs were hand-fed on two restricted scales (80 and 90% of the ad libitum feeding intake of the previous experiments) in order to obtain by regression an estimation of the maintenance requirements of HS and HR pigs. Total metabolizable energy (ME) intake and total energy retention (from empty body analyses) were measured. In the HS pigs, only 34% of the ME intake was retained compared to 38% for the HR pigs. The possibility cannot be excluded that this difference, besides the less efficient energetic conversion of the ME for production in the HS pigs, is partly due to a higher metabolic rate in these pigs at maintenance energy level. In the three experiments, no consistent differences were noted between HS and HR pigs with regard to serum levels of thyroid hormones, but there was a significantly higher response to serum insulin after a meal in the HR pigs than in the HS pigs.

Fiber types and metabolic characteristics in muscles of wild boars, normal and halothane sensitive swedish landrace pigs

1. 1. Muscle fiber characteristics, glycogen content and enzyme activities were studied in muscles of six Swedish landrace pigs, six wild boars and in three halothane sensitive landrace pigs. 2. 2. The wild boars have a higher proportion of type I and IIA fibers compared with Swedish landrace pigs. Fiber composition is similar in landrace pigs and halothane sensitive landrace pigs. 3. 3. The wild boars revealed the highest citrate synthase (CS) and 3-OH-acyl-CoA dehydrogenase (HAD) activities and the lowest glycogen content compared with the other two groups. Lower CS and HAD activities were observed in the halothane sensitive pigs compared with the other pigs. 4. 4. The data show that wild boars have a higher and halothane sensitive landrace pigs a lower aerobic capacity in skeletal muscles compared with Swedish landrace pigs.

Relationship between Ca 2+ release, sarcoplasmic Ca 2+, glycolysis and meat quality in halothane-sensitive and halothane-insensitive pigs

Post-mortem assessment of porcine stress susceptibility and meat quality by measurements of mitochondrial calcium (content and rate of release), water-holding capacity, pH at 1h post mortem and colour on M. longissimus dorsi confirm the usefulness of the halothane test for detecting stress susceptibility. Good correlations were observed between halothane sensitivity and meat quality. Post-mortem samples of M. longissimus dorsi of halothane-sensitive pigs showed significantly higher levels of sarcoplasmic calcium than similar muscle from halothane-insensitive pigs. This strongly suggests that elevated sarcoplasmic calcium levels are linked to the formation of PSE meat.

Investigation of malignant hyperthermia: analysis of skeletal muscle proteins from normal and halothane sensitive pigs by two dimensional gel electrophoresis.

Two dimensional gel analysis of skeletal muscles from normal pigs and from pigs which were homozygous for halothane sensitivity showed no obvious differences in the patterns of spots attributed to the major contractile proteins and glycolytic enzymes. In muscle from a sensitive pig which died of heat shock under anaesthesia there was a selective loss of glyceraldehyde-3-phosphate dehydrogenase and aldolase, presumably owing to proteolytic activity. The progressive loss of these enzymes under anaesthesia could contribute to the mechanism of heat production by diverting fructose 1,6 diphosphate into a futile cycle.

The Influence of the Halothane Test on Heart Parameters, Oct-Activity, Acid-Base Balance and Blood Electrolytes in Halothane-Sensitive Pigs and in Pigs Pre Medicated with a β-Blocker (Propranolol)

The heart and liver functions, blood electrolytes and acid-base balance were studies in halothane-sensitive and nonsensitive pigs. An inhibition of the hyperthermia reaction was attempted by an i.v. injection of propranolol. The pulse rate of sensitive pigs was shown to be elevated already at the beginning of halothane narcosis. No other differences between sensitive and nonsensitive pigs were observed from the electrocardiogram. Ectopic beats and arythmia appeared only in 1 halothane-sensitive pig which died soon after the test. The serum OCT-activity showed no abnormalities. Hyperkalemia and acidosis occurred but the Ga++ was not elevated in halothane-sensitive animals. The slight elevation in Na+ was thought to be caused by hemoconcentration. A propranolol injection only delayed but did not inhibit the halothane reaction.

Biochemical and Histochemical Properties and Fibre Distribution of Muscles in Trained, Untrained and Halothane Sensitive Pigs

(1978). Biochemical and Histochemical Properties and Fibre Distribution of Muscles in Trained, Untrained and Halothane Sensitive Pigs. Acta Agriculturae Scandinavica: Vol. 28, No. sup21, pp. 357-364.

Some Parameters Related to the Aerobic Capacity in Trained, Untrained, and Halothane Sensitive Pigs

Some Parameters Related to the Aerobic Capacity in Trained, Untrained, and Halothane Sensitive Pigs