Guanine nucleotide regulatory protein alterations in young Milan hypertensive strain rats

Vascular smooth muscle cell membranes from prehypertensive rats of the Milan hypertensive strain (MHS) were used to examine adenylyl cyclase activity and its regulation by guanine nucleotide regulatory proteins (G-proteins). Basal adenylyl cyclase activity was similar in MHS and Milan normontensive strain (MNS) membranes. Forsokolin (10^?4 M) produced a significantly greater stimulatory response in MHS membranes, but this was not observed with NaF (10^?2 M). Isoporterenol (10^?4 M) caused a significantly decreased stimulation of adenylyl cyclase activity in MHS membranes, while prostaglandin E₁ (10^?5 M) produced similar responses in the two strains. G_i function and GTP responses, as observed by biphasic effects of GTP on isoproterenol-stimulated membranes, were similar in both strains. The levels of G_i2α and G_qα/G₁₁α were similar in the two strains, while the levels of G_sα (44 and 42 kDa forms) and the β-subunit were significantly reduced by ～20% in MHS membranes. The α-subunit of G_i3 was dramatically reduced by ～80% in MHS membranes. The affinities of β-adrenergic receptors for the antagonist, cyanophindolol, were similar in the two strains; however, the number of β-adrenoceptors was substantially reduced in MHS membranes. These findings may be of relevance to altered vascular reactivity and transmembrane ion distribution observed in the MHS.     

N-acetyl- -arginine ethyl ester synthesis catalysed by bovine trypsin in organic media

The bovine trypsin-catalysed synthesis of N-acetyl-MHS9-4-B/0?wchp=dGLbVlW-zSkzS" alt="Image" title="Image" style="vertical-align:bottom" border="0" height=11 width="12"/> -arginine ethyl ester from N-acetyl-MHS9-4-B/0?wchp=dGLbVlW-zSkzS" alt="Image" title="Image" style="vertical-align:bottom" border="0" height=11 width="12"/> -arginine and ethanol was studied in various organic solvents (dimethyl sulfoxide, dioxane, dimethylformamide, acetonitrile, acetone, tetrahydrofuran, chloroform, toluene, carbon tetrachloride, cyclohexane and n-hexane). The highest yield was achieved in acetonitrile after incubation for 6 or 24 h. The optimal conditions for ester synthesis in acetonitrile for 6 h were as follows: 5.0 mM N-acetyl-MHS9-4-B/0?wchp=dGLbVlW-zSkzS" alt="Image" title="Image" style="vertical-align:bottom" border="0" height=11 width="12"/> -arginine, 10.0 M ethanol, 7.2 mg trypsin, 2.87% water, total volume 10.3 ml, pH 7.0 and 30°C. The hydrolytic activity of trypsin was determined after incubation for 6 days, when 87.7% of the original activity remained, suggesting that acetonitrile caused little inactivation of the enzyme. The synthetic reaction resulted in a maximal 79.3% conversion under optimized conditions after incubation for 48 h.     

In Vivo 31P NMR Spectroscopy Studies of Halothane Induced Porcine Stress Syndrome. No Effect of C-Phenyl N-Tertbutyl Nitrone (PBN)

Porcine stress syndrome (PSS) which is an example of malignant hyperthermia (MH) in swine has previously been attributed to oxidative stress primarily due to an inherited antioxidant abnormality in MH susceptible (MHS) animals. C-phenyl-N-tert-butyl nitrone (PBN), a free radical spin trap, was selected to investigate whether free radicals are involved in MH. If free radicals cause the MH stress attack, then PBN should alter the time required for the onset of the stress attack, or perhaps protect the animal from experiencing the stress attack. In vivo phosphorus-31 (³¹P) magnetic resonance spectroscopy (MRS) was used to monitor metabolism in three to four week old normal and MHS piglets administered halothane as the stress challenge. Malignant hyperthermia was not reproducibly induced by halothane anesthesia. For those animals which did develop MH a dramatic fall in the level of PCr and a rise in the level of Pi was detected by ³¹P MRS. Intravenous administration of PBN prior to halothane exposure had no effect on the number of animals experiencing the stress attack. PBN does not appear to prevent, delay or reverse the onset of halothane-induced MH in three to four week old MHS piglets. The primary events leading to the MH syndrome do not appear to be influenced by the intervention of the type of free radicals normally trapped by PBN.     

Proceedings of the Second International Bovine Lymphocyte Antigen (BoLA) Workshop

The results of the second International BoLA Workshop, held in Wageningen, Netherlands in July 1980, are reported. These results arise from a comparison of 362 alloantisera to bovine lymphocytes, originating from 9 laboratories. The an-tisera were tested against a selected panel of 144 lymphocyte samples, originating from 7 laboratories. Some of the antisera and lymphocytes had also been tested during the First International BoLA Workshop in 1978.
Ten of the eleven specificities defined at the first workshop were confirmed, and an additional six new specificities were designated. Two of the additional specificities are subgroups of the w6 specificity. The data from this workshop are consistent with the hypothesis that BoLA antigens are controlled by a series of codominant alleles at a single autosomal locus.     

Relationships among alterations in renal membrane sodium transport,renin and aminopeptidase M activities in genetic hypertension

Rats of the Milan Hypertensive Strain (MHS) may be considered a useful model for understanding the genetic molecular mechanism underlying a primary form of hypertension in at least a subgroup of patients. Many differences between MHS and its normotensive control strain (MNS) were found at the organ, cellular and biochemical level. In the present investigation renal cell membrane proteins (BBMV) were analysed by two-dimensional electrophoresis and a difference between MHS and MNS was shown in a polypeptide of 32 kDa, subsequently identified as the C-terminal fragment of aminopeptidase M (APM). The activity of the enzyme was higher in MHS. Genetic relationships between this enzyme and the other biochemical cellular abnormalities of MHS, namely sodium transport in BBMV and renin activity in kidney cortex were investigated in MHS, MNS and in two inbred recombinant strains. This analysis showed that faster sodium transport, low kidney levels of renin and hypertension, but not differences in two-dimensional electrophoretic pattern and in aminopeptidase M activity, cosegregated in recombinant strains. These results are consistent with the hypothesis that the faster sodium transport can be considered a primary cellular abnormality responsible for hypertension in MHS and that the aminopeptidase difference is not involved in the cellular abnormalities.     

Analysis of alloantisera against bovine lymphocytes. Joint report of the 1st International Bovine Lymphocyte Antigen (BoLA) Workshop

The results and agreements of the 1st international BoLA workshop, held in Edinburgh, Scotland in August 1978, are reported. Most of these concern the results from a comparison test of 249 alloantisera to bovine lymphocytes, the antisera being contributed by 9 laboratories. These sera were compared directly in Edinburgh on a panel of lymphocytes from 130 cattle of 21 breeds. In the micro-lymphocytotoxicity test used 75% of the sera reacted. Sixty eight of these sera were grouped into clusters according to their reaction patterns against the lymphocyte panel. Eleven of these clusters were clearly defined and were given workshop BoLA designations. In addition 22 sera were assigned to subgroups of the agreed clusters. There was no evidence that the method of production of the sera had any effect on their specificity.
Although genetic data was not available, the phenotypes of the test panel of lymphocytes are consistent with the clusters detecting antigens controlled by multiple alleles at a single autosomal locus. It was agreed to name the genetic region where this putative locus is located BoLA (bovine lymphocyte antigen).