The presence of peptide histidine isoleucine immunoreactivity (PHI-IR) in the retinae of male Wistar rats has been demonstrated using a specific radioimmunoassay (RIA), immunohistochemistry (IHC) and high performance liquid chromatography (HPLC). PHI levels (mean +/- S.E.M.) of 16.68 +/- 1.61 ng/g wet weight of normal retinal tissue were measured by RIA. IHC showed PHI-IR to be localized to a population of amacrine cells distributed along the proximal aspect of the inner nuclear layer and to processes in laminae I and IV of the inner plexiform layer. PHI-IR in retinal extracts was shown to coelute with a synthetic porcine PHI standard on a reverse phase HPLC system. Additionally levels of PHI-IR were significantly increased (P less than 0.001) with light adaptation.

Adaptation, Ocular↗

PubMedDate not supplied

Substance P and gastrin releasing peptide in bovine mesenteric lymphatic vessels: chemical characterization and action.

Alcoholic extracts of bovine mesenteric lymphatic vessels were assayed for the presence of SP, GRP, VIP, PHI, GIP and NT using specific radioimmunoassays. SP and GRP immunoreactivities were detected at concentrations of 190 +/- 20 and 1,000 +/- 130 pg.g-1, respectively. No significant levels of immunoreactivity were detected for any of the other peptides. SP and GRP immunoreactivities coeluted with their synthetic counterparts from both Sephadex G-50 and reversed phase HPLC columns. Synthetic SP (10(-9)-10(-7) M) and the naturally occurring analogue of GRP, bombesin (10(-9)-10(-7) M), increased spontaneous contraction rate in isolated vessel segments. This excitatory effect was not blocked by the alpha-adrenoceptor antagonist phentolamine (3 x 10(-6) M).

Animals↗

PubMedDate not supplied

Differential processing of the neurotensin/neuromedin N precursor in the mouse.

Posttranslational processing of the neurotensin/neuromedin N (NT/NN) precursor has been investigated in mouse brain and small intestine by means of region-specific radioimmunoassays coupled to chromatographic fractionations. In brain, total NT/NN immunoreactivity measured with a common C-terminal antiserum was 15.72 pmol/g. NT measured with an N-terminal antiserum was 9.74 pmol/g and NN measured with an N-terminal antiserum was 5.98 pmol/g. In small intestine, combined NT/NN immunoreactivity was 108.55 pmol/g, consisting of 66.37 pmol/g NT but only 0.96 pmol/g NN. Gel permeation chromatography and reverse phase HPLC revealed that the large discrepancy in the NT and NN values obtained in small intestinal extracts was due to the presence of a high molecular weight, hydrophobic peptide, which was reactive only with the common C-terminally directed antiserum. Pepsinization of this generated an immunoreactive peptide with similar chromatographic characteristics to NN. In mouse intestine, NN is only partially cleaved from the common NT/NN precursor, resulting in the presence of an N-terminally extended molecular species. This novel molecular species of neuromedin N may be the physiological mediator of certain peripheral biological effects hitherto attributed to neurotensin or neuromedin N.

Amino Acid Sequence↗

PubMedDate not supplied

Animal model to study the relationship between immunoreactive gastrin and inflammatory arthritis.

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Adjuvants, Immunologic↗