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L Barajas

Publications and source records attributed to L Barajas.

At least 37 records · Page 2Linked to original sources
PubMed1992

Anatomy of the renal innervation: intrarenal aspects and ganglia of origin.

The intrinsic innervation of the kidney is described based on studies using ultrastructural, fluorescent, immunocytochemical, and autoradiographic techniques. The efferent sympathetic innervation reaches all the segments of the renal vasculature and to a much lesser extent the tubular nephron. The afferent renal nerves are localized predominantly in the pelvic region, the major vessels, and the corticomedullary connective tissue. The pathways of the renal innervation to the corresponding ganglia, as reported from observations resulting from the combination of axonal transport labeling and immunocytochemical methods, are presented. In the rat the ganglia of origin of the sympathetic efferent innervation include T13-L1 ipsilateral and contralateral paravertebral ganglia and the prevertebral superior mesenteric and celiac ganglia. The sensory afferent innervation presents a different segmental distribution of the dorsal root ganglia for the right and left kidney. For the left kidney, the corresponding ganglia extend from T8 to L2 with the greatest numbers in T12 and T13. For the right kidney, ganglia as high as T6 and as low as L2 harbor neurons innervating the kidney. Current knowledge of the anatomical bases of the function of the renal nerves is discussed.

Animals↗
PubMed1991

Prenatal and postnatal development of the CGRP-immunoreactive innervation in the rat kidney.

Calcitonin gene-related peptide (CGRP) immunoreactive afferent nerves were seen intrarenally by prenatal day 16. They grow rapidly and CGRP positive nerves are observed at birth associated with the arterial and venous vascular tree, forming a rich plexus in the pelvic region and in the connective tissue located near the corticomedullary region. The distribution and extent of CGRP immunoreactive nerves suggest that at birth the rat is able to provide information on the status of the kidney to be integrated in the mechanisms of body fluid homeostasis.

Aging↗
PubMed1991

Expression of epidermal growth factor in the rat kidney. An immunocytochemical and in situ hybridization study.

The renal localization and the site of synthesis of epidermal growth factor (EGF) were investigated in the rat kidney by immunohistochemistry and in situ hybridization techniques. EGF was localized in the cells of the thick ascending limb of Henle (TAL) and distal convoluted tubule (DCT). At the ultrastructural level, EGF immunoreactivity was distributed on the apical membrane and trans-Golgi complex of the TAL and DCT cells. These segments of the rat nephron also hybridized to prepro-EGF cRNA probes in a specific manner, indicating that TAL and DCT are the sites of EGF synthesis in the rat kidney.

Animals↗
PubMed1990

Identification of pro-epidermal growth factor and high molecular weight epidermal growth factors in adult mouse urine.

By use of immunoblot analysis, we demonstrate the presence of a pro-Epidermal growth factor (EGF) with an approximate molecular weight of 165 kDa in adult mouse urine. In addition, urine contains four high molecular weight EGFs with approximate molecular weights of 116, 97, 66 and 56 kDa. The 165 kDa pro-EGF as well as the 66 and 56 kDa EGFs also are detectable in mouse kidney extract. Neither urine nor kidney contain the mature EGF of 6 kDa. The 165 kDa pro-EGF is the major product synthesized in renal tissue and secreted in urine. The finding of high molecular weight EGFs in urine suggests that part of pro-EGF secreted into urine undergoes partial proteolysis distal to its site of synthesis.

Animals↗
PubMed1990

Expression of epidermal growth factor in the kidney and submandibular gland during mouse postnatal development. An immunocytochemical and in situ hybridization study.

Earlier work has demonstrated that the salivary glands and kidneys are the major sites of epidermal growth factor (EGF) synthesis in adult mice. The precise timing of the onset of endogenous EGF synthesis in these tissues is not yet clear. In the present study we assessed the ontogenesis of EGF expression in the Swiss-Webster mouse. Paraformaldehyde-fixed frozen sections of neonatal kidneys and salivary glands were probed with proEGF cRNA labelled with 35S for in situ hybridization and with rabbit antisera to mouse EGF for immunocytochemistry. Both EGF mRNA and immunoreactivity were first detected in the developing distal nephron between days 3 and 5 postpartum. Juxtamedullary nephrons underlying the superficial nephrogenic zone were the first to express EGF. During the 2nd week after birth, EGF-expressing tubules became more abundant and distributed to medullary as well as cortical regions, corresponding to the thick ascending limb of Henle and distal convoluted tubule. Initial EGF mRNA and immunoreactivity in the submandibular gland were first detected between days 18 and 20 postpartum and increased notably during the following weeks.

Animals↗
PubMed1990

Monoaminergic innervation of the rat kidney: a quantitative study.

The sympathetic innervation of the renal tubules and vasculature was characterized by measuring the overlap of accumulations of autoradiographic grains (AAGs) on these structures in autoradiograms of kidney sections from rats injected with tritiated norepinephrine. AAG overlap was used as an indirect measure of the innervation of those structures. The renal vasculature showed x 4.5 more AAG overlap than observed on renal tubules. The greatest amount of AAG overlap occurred on afferent arterioles, followed by efferent arterioles, interlobular arteries, cortical capillaries, arcuate arteries, and renal veins. High concentration of AAGs occurred along the vascular bundles of the outer stripe. In the tubular nephron the proximal tubule had the greatest amount of AAG overlap, followed by the cortical thick ascending limb of Henle, the connecting tubule, the distal convoluted tubule, and the collecting duct. It was found that afferent arterioles had significantly higher mean density of AAG overlap than efferent arterioles for the superficial, midcortical, and juxtamedullary (vascular bundles excluded) renal cortex. There was consistently more AAG perimeter facing the interstitium than overlapping the vasculature. These observations, together with the ultrastructural distribution of synaptic vesicles in varicosities, suggest that the interstitium might be an additional pathway of neurotransmitter access to the effector structures.

Animals↗
PubMed1990

Effect of thyroxine administration on the expression of epidermal growth factor in the kidney and submandibular gland of neonatal mice. An immunocytochemical and in situ hybridization study.

The effect of T4 administration on epidermal growth factor (EGF) expression in kidney and submandibular glands (SMG) was studied in newborn mice. EGF messenger RNA (mRNA) abundance and EGF immunoreactivity were assessed by in situ hybridization and immunohistochemical techniques, respectively. T4 treatment on days 0-6 augmented both the in situ hybridization and immunocytochemical signals in kidney but not in SMG on day 7. By contrast, T4 injections on days 7-14 did not alter the in situ hybridization or immunocytochemical signals in kidney but increased both signals in SMG on day 15. Thus, neonatal T4 treatment augments the levels of EGF mRNA as well as EGF immunoreactivity in both kidney and SMG. The T4 effect is manifested during the first week in kidney whereas the SMG responds to T4 treatment only during the second week of life.

Aging↗
PubMed1990

Steroid sulfatase expression in human placenta: immunocytochemistry and in situ hybridization study.

Steroid sulfatase (STS), an important enzyme in the pathway of estrogen synthesis from sulfated steroid precursors, was localized to the syncytial trophoblast of human placentas during different periods of pregnancy by using a mouse monoclonal antibody and immunocytochemical techniques. Preembedding immunoelectron microscopy revealed STS immunoreactivity associated with the rough endoplasmic reticulum of the syncytial trophoblast. STS mRNA was also localized to this outermost layer of the human trophoblast. At a cellular level, both STS message and immunoreactivity seemed to be more abundant during the late first and early second trimesters than in term placentas. Although the syncytial trophoblast is known to originate from the cytotrophoblast, neither STS immunoreactivity nor STS mRNA was detected in the cytotrophoblast at any stage of placental development studied.

Arylsulfatases↗
PubMed1989

Innervation of the renal proximal convoluted tubule of the rat.

Experimental data suggest the proximal tubule as a major site of neurogenic influence on tubular function. The functional and anatomical axial heterogeneity of the proximal tubule prompted this study of the distribution of innervation sites along the early, mid, and late proximal convoluted tubule (PCT) of the rat. Serial section autoradiograms, with tritiated norepinephrine serving as a marker for monoaminergic nerves, were used in this study. Freehand clay models and graphic reconstructions of proximal tubules permitted a rough estimation of the location of the innervation sites along the PCT. In the subcapsular nephrons, the early PCT (first third) was devoid of innervation sites with most of the innervation occurring in the mid (middle third) and in the late (last third) PCT. Innervation sites were found in the early PCT in nephrons located deeper in the cortex. In juxtamedullary nephrons, innervation sites could be observed on the PCT as it left the glomerulus. This gradient of PCT innervation can be explained by the different tubulovascular relationships of nephrons at different levels of the cortex. The absence of innervation sites in the early PCT of subcapsular nephrons suggests that any influence of the renal nerves on the early PCT might be due to an effect of neurotransmitter released from renal nerves reaching the early PCT via the interstitium and/or capillaries.

Animals↗
PubMed1989

Epidermal growth factor and the kidney.

Current information indicates that the mammalian kidney is a significant site of EGF synthesis, second only to the salivary gland in the rodent and probably exceeding most other tissues in the human species. The prepro EGF mRNA is localized to the cells of the TALH and the DCT. The EGF mRNA transcript in kidney is similar to that in salivary gland; the molecular mass of the prepro EGF protein in kidney approximates 130,000 kDa. Several EGF peptides are excreted in urine, including 6000-molecular weight peptides (composed of EGF 1-53, 1-52, 1-51, and 1-50) and a 30,000-molecular weight species with an aminoterminus portion corresponding to amino acids 829-848 of the prepro molecule. It has been suggested that prepro EGF could be a membrane protein since it contains an internal hydrophobic domain (amino acids 1039-1058) adjacent to the EGF sequence (amino acids 976-1029). The 30,000-molecular weight urinary product appears to represent a protein derived from amino acids 829 to approximately 1029 of prepro EGF, adjacent (distal) to the hydrophobic domain. Moreover, immunoelectron microscopy localizes the EGF immunoreactivity to the apical plasma membrane of the TALH and DCT cells. The molecular form of this apically localized, EGF immunoreactivity is not yet clear. Proximal, distal, and TALH cells of the renal tubules and renal medullary interstitial cells appear to have EGF receptors and respond to EGF with increased DNA synthesis and mitogenesis. Also, there is a relatively late increase in prepro EGF mRNA levels in TALH and DCT cells during the process of renal hypertrophy. Limited evidence suggests a role of EGF on tubular function mediated via basal EGF receptors. EGF peptides processed intracellularly or by membrane localized peptidases appear to be continuously excreted and secreted into urine from the apical membrane surface of the TALH and DCT cells. This urinary EGF is constantly bathing urinary tract epithelial surfaces and could play a role in maintaining surface integrity. A similar role for salivary gland EGF in saliva has been proposed for the gastrointestinal tract. It also is possible that prepro EGF is anchored in the apical membrane, where it could function as a receptor, and a role for renal tubular EGF in regulation of membrane transport events has been proposed.

Animals↗
PubMed1989

In situ hybridization of prepro-epidermal growth factor mRNA in the mouse kidney.

The presence of prepro-epidermal growth factor (prepro-EGF) mRNA was studied in the mouse kidney by in situ hybridization using [3H]prepro-EGF cDNA and 35S-labeled prepro-EGF cRNA probes. In addition, anti-EGF serum was utilized to immunolocalize the peptide by the avidin-biotin complex immunoperoxidase method. Both EGF immunoreactivity and prepro-EGF mRNA hybridization were localized to the thick ascending limb of Henle (TAL) and the distal convoluted tubule (DCT), whereas the macula densa was negative. The glomerulus, the proximal portion of the nephron, and the collecting system were negative. Computer-assisted image analysis of the optical density of the autoradiographic and immunocytochemical signals were performed. The medullary TAL expressed significantly less prepro-EGF than the cortical TAL and the DCT.

Animals↗
PubMed1988

Innervation of the thick ascending limb of Henle.

The overlap of accumulations of autoradiographic grains (AAGs) on profiles of the thick ascending limb of Henle (TALH) was measured in autoradiograms of sections from rat kidneys with monoaminergic nerves labeled by means of tritiated norepinephrine. The amount of AAG overlap was used as an indirect means of quantifying innervation along the TALHs of superficial, mid-cortical, and juxtamedullary nephrons. The density of innervation along the TALH showed nephron heterogeneity; the juxtamedullary nephrons with a high pre- and postjuxtaglomerular apparatus (JGA) TALH density of innervation and the upper and midcortical nephrons with high TALH innervation densities at the level of the JGA. The pre-JGA TALH of the juxtamedullary nephrons had a significantly higher (P less than 0.001) density of innervation than the midcortical or superficial nephrons. The TALHs of juxtamedullary nephrons were found to have substantially more innervation than the TALHs of the other nephrons. For all three populations of nephrons, the pre-JGA TALH had the greatest amount of innervation. Neural regulation of TALH function would occur mainly along the pre-JGA and level of the JGA TALH. This regulation would increase TALH NaCl reabsorption (decrease luminal NaCl concentration) and therefore influence 1) the urinary concentrating mechanism, and 2) renin secretion via the macula densa mechanism. The innervation of the TALH was predominantly associated with the vasculature of the TALH's own nephron. However, innervation associated with medullary ray capillary beds from deeper nephrons was observed on pre-JGA TALHs from superficial and midcortical nephrons.

Animals↗
PubMed1988

In situ hybridization of nerve growth factor mRNA in the mouse submandibular gland.

We studied the presence of beta-nerve growth factor (NGF) mRNA in the submandibular gland of the mouse by in situ hybridization using 35S-labeled prepro-beta-NGF antisense RNA. Female and male mice were studied at different stages of postnatal development, ranging from 3 to 12 weeks. Although NGF mRNA was detectable in the granular convoluted tubules of the submandibular gland in all the age and sex groups studied, the abundance of the signal dramatically increased after 5 weeks during the development of the submandibular gland. In addition, a conspicuous sexual dimorphism became increasingly apparent in the 6-, 7-, 10-, and 12-week-old animals, due to the remarkable development of the granular convoluted tubules in the adult male mouse, that expressed abundant NGF mRNA.

Animals↗
PubMed1987

Nerve growth factor immunoreactivity in mouse kidney: an immunoelectron microscopic study.

We have recently reported the immunolocalization of nerve growth factor (NGF) in mouse kidney by light microscopy. In the present study, we have investigated the ultrastructural localization of NGF by the preembedding immunoperoxidase method for electron microscopy. NGF immunoreactivity was present in the connecting tubule cells of the distal nephron. These cells showed immunostaining associated with the Golgi complex, vesicles, rough endoplasmic reticulum (RER), and polyribosomes. The intercalated cells, in contrast, lacked immunoreactivity.

Animals↗
PubMed1986

Immunocytochemical localization of nerve growth factor in mouse kidney.

The presence of NGF in mouse kidney was investigated using immunocytochemical methods. Female and male adult Swiss-Webster mouse kidneys were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative. The kidneys were frozen, and serial sections were prepared. Rabbit NGF antiserum was used for the primary incubation, and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. NGF immunoreactivity was localized in the apical and perinuclear cytoplasm of cells lining the late distal nephron, in a portion that corresponds to the connecting tubule. This portion of the nephron has been consistently observed in close anatomical relationship with arterioles, which are known to be richly innervated. Some cells of the connecting tubule, corresponding to intercalated cells, lacked NGF immunoreactivity.

Animals↗
PubMed1986

Immunocytochemical localization of renin and kallikrein in the rat renal cortex.

Immunocytochemical studies in the past, using alternate serial sections to localize individual antigens, concluded that there was no close relationship between renin- and kallikrein-containing structures in the rat kidney. We have investigated this relationship by simultaneously localizing renin and kallikrein in the same section using immunoperoxidase with two different chromogens. Analysis of serial kidney sections from three rats indicated that kallikrein-containing late distal tubular cells corresponded in their distribution to connecting tubule cells. They were observed in the proximity (less than 3 micrograms) of renin-containing JG cells in 66.6% of the superficial (N = 30), 46.6% of the midcortical (N = 15) and 26.7% of the juxtamedullary (N = 15) afferent arterioles surveyed. When traced through serial sections, 90% of the afferent arterioles from superficial glomeruli (N = 30), 86.7% of the afferent arterioles from midcortical glomeruli (N = 15) and 73.3% of those from juxtamedullary glomeruli (N = 15) came within 3 micrograms of a late distal tubule showing some kallikrein-positive cells. These cells were adjacent to the afferent arteriole in 67 to 80% of the arterioles surveyed. This spatial relationship suggests an anatomical basis for a possible interaction between the afferent arteriole, containing renin-positive JG cells, and kallikrein-positive late distal tubular cells.

Animals↗
PubMed1986

Immunocytochemical localization of epidermal growth factor in mouse kidney.

Epidermal growth factor (EGF) was originally isolated from mouse submandibular glands (SMG). However, SMG removal failed to lower circulating EGF, and large amounts of EGF have been found in mouse urine. In addition, the presence of pre-pro-EGF mRNA in mouse kidney has recently been reported by others. Kidneys may therefore represent an alternate source of EGF. In the present study, we investigated the immunocytochemical localization of EGF in mouse kidney. Male and female adult Swiss Webster mice were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative, the kidneys were frozen, and serial sections were obtained. Rabbit EGF antiserum was used for the primary incubation and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. EGF was immunolocalized in the apical portion of the cells lining the thick ascending limb of Henle (TALH) and the distal convoluted tubule (DCT). The macula densa, in contrast, lacked EGF immunoreactivity. No sex differences were observed in the distribution pattern or intensity of immunostaining. Infusion of EGF into sheep renal artery has been reported to induce changes in urine flow and ionic composition. Immunolocalization of EGF in the TALH and DCT documented here supports a regulatory role for EGF in the function of the mouse distal nephron.

Animals↗