Vasopressin isolation

These include nicotinic acetylcholine receptors, neuronal calcium channels, muscle sodium channels, vasopressin receptors, and iV-methyl-D-aspartate (NMDA) receptors. Some general features of the structure, function, and evolution of biologically active peptides isolated from Conus venom are presented. 

Rich, D.H., Gesellchen, P.D., Tong, A., Cheung, A., and Buckner, C.K. (1975) Alkylating derivatives of amino acids and peptides. Synthesis of N-maleoyl amino acids, l-[N-maleoylglycyl-cysteinyl]-oxytocin and l-[N-maleoyl-ll-aminoundecanoyl-cysteinyl]-oxytocin. Effects on vasopressin stimulated water loss from isolated toad bladder. J. Med. Chem. 18,1004-1010. 

The energetics of Phe provide an excellent example of this phenomenon. In our molecular dynamics simulation of vasopressin, we found that Phe underwent conformational transitions between three regions of conformational space the 7 (, = -80, -1-80), a, (, i/i = -E80, -80) conformations(64). These conformations in the isolated residue, taken as the N-acetyl, N -methylamide blocked phenylalanine, are well separated energetically as can be seen in Table I. The C7 is 3.1 Kcal more stable than the 7 , and 4.7 Kcal more stable than the a,. In order to compare the relative stabilities of these phenylalanine conformations in the... 

The energy calculated includes the Ca and CO of the previous residue and the NH and Ca of the subsequent residue in vasopressin. The energies in vasopressin and in the isolated residue are then directly comparable. 

The occurrence of a variety of neuropeptides in the brain has been discussed in Section A. The first of these to be discovered811 was the 11-residue substance P (Table 30-4), which was isolated in 1931. Like other neuropeptides it may function either as a transmitter or neuromodulator or perhaps both. Substance P, as well as many other neuropeptides, has been localized to specific neurons. Along with somatostatin, CCK, and enkephalins, it is found in high concentrations in the basal ganglia. Enkephalin and substance P are also found in specific neural elements in the visual system of lobsters.812 In some cases a neuron contains both synaptic vesicles containing a major neurotransmitter and also vesicles containing a peptide or other cotrans-mittor. The peptide pituitary hormones ACTH, MSH, and vasopressin as well as the hypothalamic neurohormones may have effects on learning and behavior.813... 

DU VIGNEAUD, VINCENT (1901-1978). An American biochemist who won the Nobel prize lor chemistry in 1955. His work involved Ihe study of the metabolism of biologically significant sulfur compounds, which led to the finding of transmethylation in mammalian metabolism. He isolated and proved the structure of Ihe vitamin biotin, and synthesized penicillin, oxytocin, and the vasopressin hormone of the posterior pituitary. His education was at Rochester. Yale. St. Louis, and George Washington Universities. 

Vasopressin and oxytocin are peptide hormones secreted from the posterior lobe of the pituitary gland. They function primarily to raise blood pressure (vasopressin), as antidiuretic (vasopressin), and to promote contraction of uterus and lactation muscies (oxytocin). The isolation, identification, and synthesis of these hormones was accomplished by Vincent du Vigneaud, for which he was awarded the Nobel Prize in chemistry in 1955. 

Vasopressin Hypophysis Isolated posterior lobe (rat P2Y) Sperlagh et al. 1999... 

Fig. 8. Effects of agonists on cytosolic Ca2+ (measured by fluorescence) in isolated rat hepatocytes loaded with Quin 2. The concentrations of agonists are Epi, 1 /uM epinephrine Phenyl, 10 fiM phenylephrine Vaso, 10 nM vasopressin Glue, 10 nM glucagon. Reproduced from Ref. 3 by permission of the authors and publisher.

Fig. 11. Potentiation by glucagon of the actions of vasopressin on the calcium and [3H]IP, content of isolated rat hepatocytes previously labeled with [3H]myo-inositol. Hepatocytes were incubated with [ H]myo-inositol to label the inositol phospholipids and then for S min with the concentrations of vasopressin shown in the presence or absence of 1 nM glucagon. Total cell calcium and [3H]IP, were measured as described in Refs. 139 and 140. Reproduced from Ref. 5 by permission of the authors and publisher.

Fig. 12. Effect of extracellular Ca2 concentration on the accumulation of Ca2+ by isolated rat hepatocytes incubated for 5 min with 10 nM vasopressin plus 10 mM glucagon. Reproduced from Ref. 160 by permission of the authors and publisher.

Pitzel L, Konig A (1984) Lack of response in the release of oxytocin and vasopressin from isolated neurohypophyses to dopamine, met-enkephalin and leu-enkephalin. Exp Brain Res 56 221-226. 

Also, prolylendopeptidase inhibitory peptides (PEP) have been found in wines (Yanai et al. 2003). PEP may have a role in the degradation of biologically active peptides containing proline, such as oxytocin, vasopressin, substance P, bradykinin, neurotensins and angiotensins. Two inhibitory peptides have been isolated and characterized, Pep A (Val-Glu-Ile-Pro-Glu) and Pep B (Tyr, Pro, He, Pro, Phe). Both of them showed PEP inhibition, thereby suppressing the degradation of neuropeptides, vasopressin, substance P and fragments 8-13 of neurotensin, which are involved in memory and neural communication. 

Angiotensin II receptors [152], endothelin receptors [153] and vasopressin Via receptor (VlaR) and V2 receptor (V2R) receptors [154] have been isolated in rat arterioles. In isolated rabbit arterioles, the vasoconstrictor response of angiotensin II is counteracted by vasoddatory prostaglandins and nitric oxide [155]. The calcium response to angiotensin II in the isolated rabbit afferent arteriole shows tachyphylaxis [156]. This... 

Arginine vasopressin (AVP) is a potent vasoconstrictor that preferentially reduces renal medullary blood flow through the stimulation of the vasopressin Via receptor (VlaR). Studies have also shown that the vasopressin V2 receptor (V2R) may modulate AVP-mediated vasoconstriction. The transcriptional and translational sites of the VlaR and V2R in micro-dissected intrarenal vascular segments from both the cortex and medulla was studied [154]. The results indicate that VlaR mRNA and proteins are present in the isolated cortical or medullary vasculature, but the V2R mRNA and proteins were not found. This study suggests that the vasoconstrictor action of AVP within the renal medulla is mediated through the VlaR and that the modulatory V2R- mediated vasodilation is probably through the release of paracrine hormones found within the renal interstitial or tubular cells. 

Hayakawa H, Hirata Y, Suzuki E, SugimotoT, Matsuoka H, Kikuchi K, Nagano T, Hirobe M Mechanisms for altered endothelium-dependent vasorelaxation in isolated kidneys from experimental hypertensive rats. Am J Physiol 264 1535-41,1993 Hirata Y, Hayakawa H, Kakoki M,Tojo A, Suzuki E, Nagata D, Kimura K,Goto A, Kikuchi K, NaganoT, Hirobe M, Omata M Receptor subtype for vasopressin-induced release of nitric oxide from rat kidney. Hypertension 29 58-64,1997 Hirata Y, Hayakawa H, Suzuki E, Omata M Does endothelin work as an intrarenal mechanism to alter pressure natriuresis in spontaneously hypertensive rats J Hypertens 12 251-7,1994... 

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