RT-PCR study of the distribution of connexin 43 mRNA in the glomerulus and renal tubular segments

An RT-PCR study of the distribution of connexin 43 (Cx43) mRNA in glomeruli and along the rat tubular segments was carried out to establish the differential expression of Cx43 in the different segments of the tubule, in renal regions, in isolated glomerular preparations (IGP), and in microdissected glomeruli. The mRNA level of Cx43 in macrodissected renal regions appeared in the following order: inner papilla > outer papilla and IGP > outer medulla and cortex. Among the microdissected tubules, inner medullary collecting ducts (IMCD) expressed the highest level of Cx43 mRNA, followed by the cortical collecting ducts (CCD). The proximal convoluted tubules and proximal straight tubules expressed significantly less Cx43 than the IMCD, glomeruli, and CCD. Medullary thick ascending limb and distal convoluted tubules showed the lowest level of Cx43 mRNA. The RT-PCR results of the microdissected segments correlate well with those obtained by RT-PCR of the renal regions. The high concentration of Cx43 mRNA in the IMCD together with the observation of abundant punctate immunofluorescence for Cx43 suggests that the IMCD not only expresses Cx43 mRNA but also that the mRNA is translated to Cx43 protein.

Evidence for NOS-containing renal neuronal somata transiently expressing a catecholaminergic phenotype during development in the rat

Transiently catecholaminergic cells (TC-cells) expressing tyrosine hydroxylase (TH) have been shown in a variety of tissues during embryonic life. To investigate the possible relationship of nitric oxide synthase (NOS)-containing renal neuronal somata (RNS) and the TC-cells, we examined serial 100 microm slices of whole kidneys for TH-immunofluorescence and NADPH-d histochemistry during prenatal and postnatal development. The number of TH-cells increased during the prenatal period, peaked at birth and were very rare by PD21. A subpopulation of TH-immunoreactive RNS displayed NADPH-d activity. By PD21 the TH-positive RNS had practically disappeared while the number of NADPH-d positive RNS was markedly increased. These results suggest that kidneys possess transient catecholaminergic cells which display NOS-activity and that NOS expression may be the end-point in the differentiation of the RNS.

Clinically silent primary adrenal lymphoma: a case report and review of the literature

Primary adrenal lymphoma (PAL) is extremely uncommon. We describe a case of clinically silent non-Hodgkin's B-cell lymphoma of diffuse large cell type with exclusive left adrenal localization. The tumor was discovered by computed tomography (CT) as a 2.5-cm dense mass and diagnosed at autopsy. Literature concerning this unusual neoplasm is reviewed. During the early stage, particularly when the lesion is small, PAL is likely to be missed. This unusual entity should be included in the differential diagnosis of adrenal masses so that early diagnosis may be made and intervention might dramatically affect the clinical outcome.

Omphalocele with absent radial ray (ORR): a case with diploid-triploid mixoploidy

We observed omphalocele, absence of radii, hypoplasia of one humerus, a hemivertebra, and syndactyly in a stillborn male at 22 weeks of gestation. Craniofacial and genitourinary abnormalities were absent. DNA measurement by flow cytometry on a paraffin-embedded autopsy specimen showed 32% triploid cells. ORR (omphalocele-radial ray) complex appears to be a consistent combination, and diploid-triploid mixoploidy may be one of its causes.

Mice lacking transforming growth factor alpha have an increased susceptibility to dextran sulfate-induced colitis

BACKGROUND & AIMS

There is indirect evidence that transforming growth factor alpha (TGF-alpha) is an important mediator of mucosal defense and repair. TGF-alpha knockout mice and TGF-alpha-deficient mice (wa-1) provide novel approaches to evaluate the role of TGF-alpha in preserving the integrity of the colon.

METHODS

Colitis was induced by oral administration of dextran sodium sulfate (DSS, 5 g/dL) to knockout mice, their genetic controls (GC), wa-1 mice, and BALB/c mice. TGF-alpha was also administered intraperitoneally to wa-1 mice to evaluate the effect of exogenous TGF-alpha in DSS colitis.

RESULTS

In response to DSS, nearly 60% of the entire colonic mucosa was destroyed in knockout and wa-1 mice, compared with 22% in GC mice and 16% in BALB/ c mice. Body weight loss was doubled in knockout (28%) and wa-1 mice (23%) compared with GC (11%) and Balb/c mice (12%). TGF-alpha application to wa-1 mice reduced the severity of mucosal injury by almost 70% compared with controls.

CONCLUSIONS

The marked susceptibility of TGF-alpha knockout and wa-1 mice to DSS and the obvious amelioration of the colonic injury by exogenous TGF-alpha application in wa-1 mice suggest that TGF-alpha is a mediator of protection and/or healing mechanisms in the colon.

Cell-specific protein and gene expression in the juxtaglomerular apparatus

1. The juxtaglomerular apparatus (JGA) consists of a tubular component, the macula densa (MD), attached to a vascular component consisting of the afferent and efferent arterioles and the extraglomerular mesangium. The JGA is richly innervated by sympathetic fibres. 2. The MD is morphologically, histochemically and functionally different from the ascending thick portion of the loop of Henle where it is located. 3. The vascular component includes the vascular smooth muscle cells of the arteriole, the renin-producing cells or juxtaglomerular cells, extraglomerular mesangial cells (Goormaghtigh cells) and endothelial cells. They are coupled by gap junctions. 4. Physiological evidence indicates that the composition of tubular fluid at the MD regulates renin secretion and glomerular haemodynamics and that the JGA is important in the maintenance of body salt-water homeostasis. Evidence suggests that the MD exerts its action on the vascular component through a paracrine mechanism.

Transforming growth factor alpha-immunoreactivity in neural tissues of the rat stomach

We report TGF alpha immunoreactivity in neurons of the myenteric plexus and in nerve fibers in the muscle and submucosal layers of the rat stomach. Association of TGF alpha staining nerve fibers to vessels and smooth muscle cells gives morphological evidence that EGF/TGF alpha's actions to increase mucosal blood flow and gastric motility may be mediated by TGF alpha derived from neural structures. These data suggest that TGF alpha plays a role in the neural control of the gastric function.

Bile ductule formation in fetal, neonatal, and infant livers compared with extrahepatic biliary atresia

The cell of origin of intrahepatic bile ducts during fetal development remains a subject of controversy, although there has been recent evidence that they form from hepatocytes. However, the origin of neoductules and ducts in the setting of liver disease has not been extensively investigated in humans. Using anticytokeratins characteristic of hepatocytes and bile ducts, we repeated earlier studies of fetal development to compare ductule formation in normal developing and newborn livers with the ductules formed during extrahepatic biliary atresia. We utilized an antibody to proliferating cell nuclear antigen (PCNA) staining to determine which cells were in active DNA synthesis (S phase) during fetal development and liver disease progression. The results indicated that hepatocytes undergo a phenotypic switch (metaplasia) to form ductular cells during fetal development. There was no ductular cell replication in the fetal livers. In contrast, both bile ductular metaplasia and proliferation were observed in biliary atresia. Therefore, both a limiting plate phenotypic switch to ductules and replication of ductular cells play a role in the increase in the ductules seen in the progression to biliary cirrhosis. Bile ductular proliferation in biliary atresia, however, was less than that seen in hepatocytes, whereas the number of bile ductules increased and the relative proportion of hepatocytes diminished as the accompanying periductular fibrosis progressed to cirrhosis.

Distribution of nitric oxide synthase-containing ganglionic neuronal somata and postganglionic fibers in the rat kidney

Nitric oxide synthase (NOS)-immunoreactive neurons were identified in the rat kidney by using an antibody against type Ia NOS and the avidin-biotin complex immunoperoxidase method in whole kidneys examined in 100 microns serial sections. The histochemical method for demonstration of the nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) was also used to characterize NOS-containing neurons. All somata showing NOS immunoreactivity also displayed NADPH-d activity. The greatest number of neuronal somata were observed in groups at the wall of the renal pelvis and in the angular space formed by the pole of the renal parenchyma and renal pelvic wall. They were also seen at the renal hilus close to the renal artery and along the interlobar vasculature. The size of the neuronal somata in the 35-day-old rat ranged from 13.6 to 34.8 microns, with a mean size of 21.52 +/- 4.81 microns. Seventy percent, however, ranged in size from 17.8 to 26.8 microns. The shape of the neuronal somata also varied, with the majority having an ovoid or round shape. The distribution of the postganglionic fibers was investigated by means of the camera lucida. Postganglionic fibers projected into the wall of the renal pelvis and/or to the interlobar arteries extending to the arcuate arteries and to the beginning of the afferent arterioles. The NOS-immunoreactive neurons may have a vasodilator and relaxing function on the renal pelvic wall and vasculature. In addition, the presence of NOS-containing nerve fibers in nerve bundles, which are known to have predominantly vasomotor and sensory fibers, suggest that they may have a possible modulatory role on renal neural function.

Development of NOS-containing neuronal somata in the rat kidney

An investigation of the changes in size, number and distribution of NOS-containing neuronal somata in the rat kidney was undertaken. The immunoperoxidase method for the staining of NOS and the histochemical method for the demonstration of NADPH-d were applied to serial thick sections (100 microns) of whole kidneys. Animals at embryonic day 14 (ED14), ED16, ED18, ED20, at birth (PD0), and at postnatal days 4 (PD4), PD12, PD21 and PD35 were studied. NOS-containing neuronal somata were observed by the 20th day of gestation in some kidneys and were consistently seen at birth. They were usually seen in groups of separated neuronal somata or in tight clusters. The neuronal somata were often attached or embedded in nerve bundles. As the kidney developed, the number of neuronal somata separated from each other increased, while the number of clusters remained relatively constant. The size of the neuronal somata increased with development. There were highly significant statistical differences in the size of the neuronal somata between all groups, except between PD12 and PD21. The distribution of neuronal somata at birth was similar to that of the adult. They could be found, (a) at the free renal pelvic wall; (b) in the connective tissue at the angular space between the renal pelvis and the renal parenchyma (SPP); and (c) along the interlobar vessels. At birth and in the early stages of development, the greatest number of neuronal somata were located at the renal pelvis. In the later stages of development, more neuronal somata appear in the connective tissue between the renal pelvis and the renal parenchyma. The location of NOS-containing neuronal somata suggests that they might have a modulatory role on the sympathetic and sensory renal nerves all through development.

Colocalization of NADPH-diaphorase and dopamine beta-hydroxylase in the neuronal somata of the rat kidney

Neuronal somata in the rat kidney are very often part of ganglionated plexus and contain nitric oxide synthase (NOS). Examining serial 100 microns slices of whole kidneys, we identified three subpopulations of neuronal somata by: (a) staining for NADPH-diaphorase (NADPH-d) histochemistry followed by the demonstration of dopamine beta-hydroxylase (DBH) by immunoperoxidase, and (b) staining for DBH by immunofluorescence followed by the demonstration of NADPH-d histochemical activity. The largest subpopulation of neuronal somata displayed both DBH immunoreactivity and NADPH-d histochemical activity. The second largest group of somata showed NADPH-d activity only. A small group of neuronal somata showed only DBH immunoreactivity. The presence of catecholaminergic characteristics in NOS-containing neuronal somata is unusual and raises the question as to their origin. Their heterogeneity suggests different functions for the different subpopulations.

Localization of connexin43 in rat kidney

The localization of connexin43 (Cx 43) in rat kidney was investigated by the indirect immunofluorescence technique with polyclonal antisera raised against Cx 43. Cx 43 is a gap junction protein expressed in a variety of tissues. The typically punctuated gap junction immunofluorescence (GJI) was observed in the renal arterial and arteriolar system. In the renal artery the GJI was concentrated in the media. In the juxtamedullary nephrons, the GJI is particularly abundant in the vascular bundles. There is abundant GJI in the extraglomerular mesangium while in the afferent arteriole GJI appears decreased. Abundant GJI was observed in the inner medullary collecting ducts and pelvic epithelium. The localization of Cx 43 immunofluorescence observed in this study is only in partial agreement with the results of ultrastructural investigations on the distribution of gap junctions in the kidney. An extensive tight junctional system has been demonstrated in the collecting duct system. However, gap junctions have been reported to be absent. Further studies to resolve this discrepancy are required.

Renal tubular dysgenesis: evidence of abnormality in the renin-angiotensin system

Renal tubular dysgenesis is an autosomal recessive condition characterized by short, abnormally developed cortical tubules that lack proximal differentiation. Despite the lack of normal proximal tubules, the major site of water resorption in the kidney, the principal clinical manifestations are caused by fetal and neonatal oliguria. The kidneys in three cases of neonatal renal tubular dysgenesis were found to contain large amounts of immunohistochemically reactive renin in preglomerular arterioles, glomerular hilums, and glomerular mesangial areas, far exceeding the intensity of staining and the numbers of sites stained in control kidneys. The increased accumulation of renin may reflect strong local vasoconstriction, which is responsible for reduced glomerular perfusion. This accumulation suggests faulty feedback control of renin secretion, the basis of which is still to be identified.

Rat connexins 30.3 and 31 are expressed in the kidney

Six connexin genes have previously been shown to be expressed in the rat kidney. Given the structural and functional diversity of the kidney, we hypothesize that other connexin genes may be expressed. We have partially screened a rat kidney cDNA library using low-stringency hybridization conditions with cDNA probes from rCx 43 and rCx 26 and report here the isolation of two connexin cDNA clones, rCx 30.3 and rCx 31, that have not previously been shown to be expressed in the rat kidney. Furthermore, rCx 30.3 utilizes two distinct transcripts in the kidney, while rCx 31 utilizes two transcripts in skin but only one in the kidney.

Nitric oxide synthase immunoreactive neurons in the rat kidney

The presence of neurons with nitric oxide synthase (NOS) immunoreactivity was investigated in the rat kidney. Whole kidneys were examined by means of serial sections. The indirect immunocytochemical technique using polyclonal antibody raised against rat brain type Ia NOS and the histochemical technique for nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase are used in this study. NOS-immunoreactive (NOS-IR) neurons varied in size and were observed: (1) associated with nerve bundles at the hilus of the kidney, (2) in the proximity of the lower or middle portion of the interlobar arteries, and (3) on the wall of the renal pelvis. We are presenting anatomic evidence for the presence of neurons in the rat kidney. Their location is consistent with the existence of a parasympathetic innervation of the rat kidney.

The rat renal nerves during development

The prenatal and postnatal development of the innervation of the rat kidney has been investigated using immunocytochemical methods. The efferent innervation was studied using dopamine-beta-hydroxylase and neuropeptide Y antibodies. Calcitonin gene related peptide and substance P antibodies were used to investigate the afferent innervation. Kidneys from embryos of 14 to 20 days, from newborn rats, and from animals of 4, 10, 12, 21, 38, 60, and 90 days of age were studied. Slices of whole kidneys were analyzed, and frozen sections were used to investigate the location of the nerves in more detail. Both afferent and efferent nerves are observed inside the kidney by embryonic day 16. At birth, the afferent nerves are found (1) forming a rich plexus in the renal pelvis; (2) associated with the renal vasculature as far as the interlobular arteries (cortical radial arteries) and (3) in the corticomedullary connective tissue. The efferent innervation appears, at birth, to extend to the interlobular arteries and to the afferent arterioles of the perihilar juxtamedullary nephrons. The efferent innervation increases rapidly during the following days, and by postnatal day 21 a distribution of the innervation similar to that of the adult is observed. While the afferent innervation reaches the major target regions of the kidney by birth, the efferent does most of its expansion into the kidney postnatally. Afferent and efferent fibers are found, extrarenally and intrarenally, in the same nerve bundles. This proximity between afferent and efferent fibers may represent anatomical bases for their interaction in the adult as well as during development.

The renal nerves in the newborn rat

Immunocytochemical methods were used to investigate the distribution of afferent [calcitonin gene-related peptide-(CGRP) immunoreactive and substance P-immunoreactive] nerves and efferent (neuropeptide Y-immunoreactive and dopamine beta-hydroxylase-immunoreactive) nerves in the kidneys of rats within the 1st day of life. The newborn rat kidney possesses an afferent and efferent innervation. Both afferent and efferent nerves reach the kidney in the same bundles. The afferent sensory fibers predominate overwhelmingly in the renal pelvis and ureter while the efferent fibers clearly predominate in the vasculature. The corticomedullary connective tissue contains both types of innervation with a more prominent afferent innervation (CGRP immunoreactive). Only afferent arterioles of perihilar nephrons were innervated by efferent sympathetic fibers. The distribution and extent of afferent and efferent innervation is consistent with the renal nerves playing a significant role in the transition from fetal to newborn life. The close proximity between afferent and efferent fibers suggests a possible interaction between the two systems.

Lack of control of renin release by adrenergic nervous system in the aglomerular toadfish

Aglomerular toadfish, Opsanus tau, release renin in response to hemorrhage or vasodilator drugs, presumably by stimulating a renal arterial baroreceptor. We aimed to determine whether the adrenergic nervous system and prostaglandins play a role in the control of renin release in unanesthetized toadfish kept in 50% seawater. Isoproterenol (1 microgram/kg) increased plasma renin activity (PRA) fourfold and decreased blood pressure (BP); both effects were abolished by a concomitant infusion of propranolol. Propranolol itself slightly decreased the basal level of heart rate and BP, but not that of PRA. Norepinephrine (1 microgram/kg) increased BP, but did not change PRA. Repeated injection of 6-hydroxydopamine did not alter resting levels of either PRA or BP. Monoamine-specific nerve fluorescence activity could not be demonstrated in association with arterioles of kidneys from intact toadfish or from those treated with monoamine oxidase inhibitor and norepinephrine (5 mg/kg). Furthermore, treatment of toadfish with indomethacin (10 or 20 mg/kg) prevented neither the increase in PRA nor the reduction in BP after a massive hemorrhage. These results indicate that renin release in toadfish primarily occurs in response to a reduction in renal arterial pressure, whereas it appears unlikely that the adrenergic nervous system or prostaglandins have a significant role in the control of renin release.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Immunoelectron microscopy of epidermal growth factor in mouse kidney

We recently have reported the immunolocalization of epidermal growth factor (EGF) in mouse kidney by light microscopy. In the present study, we have investigated the ultrastructural localization of EGF by the preembedding immunoperoxidase method for electron microscopy. EGF immunoreactivity was present on the apical plasma membrane of the cells of the thick ascending limb of Henle and the distal convoluted tubule. The macula densa, by contrast, lacked immunoreactivity. Based on functional evidence, a possible regulatory role for EGF in the membrane transport in the distal nephron has been suggested.

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.

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.

Innervation of the late distal nephron: an autoradiographic and ultrastructural study

A study of the monoaminergic innervation of the cortical distal nephron beyond the thick ascending limb of Henle (TALH) was carried out by surveying nine autoradiograms, from three rats injected with exogenous tritiated norepinephrine, for overlapping of the tubule by accumulations of autoradiographic grains (AAGs). The largest number of the AAGs appeared on the late distal convoluted tubule-connecting tubule (LDCT-CNT) portion and the vast majority of the AAGs were related to the afferent arteriole. The distal convoluted tubule (DCT) and cortical collecting duct (CCD) showed half of their AAGs related to the efferent arterioles and capillary-interstitium although a substantial amount was associated with the afferent arterioles or arteries. Electron microscopy of reembedded autoradiograms demonstrated the presence of neuroeffector junctions with the CNT and CCD at sites of AAG overlap. The presence of adrenoceptors in the late distal nephron suggests the possibility of a local response of the nephron to the action of the adrenergic nerves shown in this study.

Innervation of the renal cortical tubules: a quantitative study

A quantitative assessment of the innervation of the different portions of the cortical tubular nephron in the rat was made using tritiated norepinephrine uptake to label monoaminergic nerves, followed by autoradiography. The proximal tubules (PT) showed the greatest number of innervated profiles (IPs) [i.e., tubular profiles overlapped by accumulations of autoradiographic grains (AAG)] followed by the thick ascending limb of Henle (TALH), the distal convoluted tubule (DCT), and the collecting duct (CD). However, the highest relative frequency of innervation (RFI), i.e., the ratio of the number of IPs to the total number of profiles surveyed, occurred in the TALH followed by the DCT and PT. The number of IPs of the CDs was too low to permit adequate statistical evaluation. The PT showed the largest number of AAGs facing the interstitium or in contact with capillaries, while the TALH had the highest number in contact with the efferent arteriole. The DCT showed a disproportionately high number of AAGs in contact with the afferent arteriole. Our results suggest that all portions of the cortical tubular nephron are under some degree of neural influence.

Vasoactive intestinal polypeptide-immunoreactive nerves in the kidney

Nerve fibers immunoreactive for vasoactive intestinal polypeptide (VIP) were demonstrated by immunocytochemistry in the dog and rat kidney. They were seen in association with the renal artery and its branches. In the dog, VIP-immunoreactive fibers were rarely seen close to small blood vessels suggestive of arterioles. The possible existence of neuroeffector junctions between VIP-positive fibers and renin-secreting juxtaglomerular cells requires further investigation. VIP-positive renal nerves, however, might have a vasodilatatory role.

Simultaneous ultrastructural visualization of acetylcholinesterase activity and tritiated norepinephrine uptake in renal nerves

In this investigation we have combined the methods of ultrastructural demonstration of acetylcholinesterase activity with electron microscopic autoradiography for the demonstration of norepinephrine uptake. The results show electron-dense deposits indicative of acetylcholinesterase activity associated with perivascular axons overlaid by concentrations of silver grains representing exogenous tritiated norepinephrine. Forty-five percent of the intervaricose regions and 19% of the varicosities overlaid by autoradiographic grains showed "moderate" amounts of cholinesterase staining. A greater proportion of autoradiographic grains was observed on the varicosities than in the intervaricose regions; however, the amount of acetylcholinesterase activity was greater in the intervaricose regions than in the varicosities. This investigation provides evidence for the presence of periaxonal acetylcholinesterase staining in adrenergic axons in the rat kidney.

Premature lambs rescued from respiratory failure with natural surfactant: clinical and biophysical correlates

Thirty-four Western mixed breed lambs were delivered prematurely at 120 days gestational age (term = 150 days). Four lambs were sacrificed at birth, and four lambs were sacrificed with the onset of respiratory failure (PCO2 greater than 80 torr) at about 30 min of age. The remaining lambs were treated by tracheal instillation with 50 mg of natural sheep surfactant lipid/kg body weight. These lambs were sacrificed 10 min, 40 min, 1.5 h and 3 h after surfactant treatment. Frequent blood gas and compliance measurements documented the clinical responses of the lambs. Lungs from treated lambs showed large increase relative to untreated lungs in air volumes as assessed by pressure-volume curves and by histology. However, the pressure-volume and histologic measurements did not distinguish between the posttreatment groups of lambs. Minimum surface tensions of alveolar washes fell from greater than 30 dynes/cm to 6.3 dynes/cm 10 min after treatment and again rose to 21.6 dynes/cm within 3 h. Minimum surface tensions correlated well with the PO2 values but not with the PCO2 values measured before sacrifice. The combination of dilated distal airways and atelectasis resulted from increasing surface tensions with time and mechanical ventilation and may explain the clinical deterioration without much change in the volume of gas within the airways.

Innervation of rat antral gastrin-producing cells

The innervation of rat antral gastrin-producing cells (G-cells) was studied by light and electron microscopy. Combination of histochemistry for acetylcholinesterase and immunofluorescence for gastrin in the same tissue section showed apparent contact between some of the G-cells and acetylcholinesterase-positive nerves. Electron microscopic observation, however, revealed gaps of 200-500 nm or more between the G-cells and the closest nerve axons which often contained large dense-cored vesicles. The latter may represent the storage sites for neuropeptides previously localized by immunohistochemistry in gastric nerves.

The juxtaglomerular apparatus: anatomical considerations in feedback control of glomerular filtration rate

The juxtaglomerular apparatus is an anatomical unit located at the hilus of the glomerulus and is believed to be involved in feedback control of renal blood flow and glomerular filtration rate. In the mammal, it consists of the glomerular arterioles and extraglomerular mesangium (the vascular component) and the macula densa (the tubular component). Juxtaglomerular granular cells are modified smooth muscle cells and are believed to be the source of renin. They are present in the vascular component, being most numerous in the afferent arteriole. The macula densa segment of the distal tubule is characterized by closely packed nuclei, the basal or lateral position of the Golgi apparatus, and dispersed mitochondria that show little association with the reduced infoldings of the basal membrane. In addition to these morphological differences, there are marked histochemical differences between the macula densa and the adjacent segments of the distal tubule. Tubule-vessel contact appears to vary in extent and ultrastructure. The macula densa forms extensive and complex contact with the extraglomerular mesangial region. Contact with the arterioles may consist of simple apposition of basement membranes. Fluorescent histochemistry and electron microscopy demonstrate a consistent monoaminergic innervation of the juxtaglomerular apparatus. Autoradiography shows that axons associated with the juxtaglomerular apparatus are able to incorporate exogenous tritiated norepinephrine. Nerve endings are observed on cells of the vascular component and less frequently on the tubules of the juxtaglomerular region.

Surfactant metabolism of newborn lamb lungs studied in vivo

Surfactant, microsomal, and lamellar body fractions were isolated from the lungs of 5-day-old lambs 0.21-55 h after the intravenous injection of radiolabeled palmitic acid. The specific activities as cpm/mumol phospholipid phosphate of phosphatidylcholine, saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine were measured. The palmitate-labeled phospholipids disappeared from the lung parenchyma with a half-life of approximately 50 h. The radiolabel disappeared from phosphatidylcholine, saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine of microsomal fractions with initial half-life values of 4.5, 4.6, 1.9, and 23.9 h, respectively. The labeled phospholipids rapidly appeared in the lamellar body fraction and accumulated in the surfactant of the lambs in a linear fashion for 35 h. The curves for the labeling of surfactant with radiolabeled saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine were similar to the curve for phosphatidylcholine.

Cupular secretion by Xenopus laevis line organs: autoradiographic evidence for incorporation of 3H-glucose and 35S-sulfate

Autoradiographic evidence for incorporation of 3H-glucose and 35S-sulfate into the cupulae of Xenopus laevis (African clawed toad) lateral line organs was obtained after injection into the dorsal lymph sacs of adult animals. Time intervals of 15 minutes to 4 hours after administration of these labeled metabolic precursors were used to examine the time course of the apparent mechanism of growth of the cupulae. Our results suggest that the two layers of accessory cells (the sustentacular cells and inner layer of mantle cells), concentrically arranged around the organ's central sensory (hair) cells, elaborate distinct cupular components. Sustentacular cells, immediately adjacent to the sensory cells, appear to produce and extrude at their exposed apices a cupular "core" substance labeled by 3H-glucose, but not by 35S-sulfate. The layer of inner mantle cells, external to the sustentacular cells, was labeled by both precursors and is spatially situated to secrete a cupular sheath enclosing the cupular core. Ultrastructural differences between the secretory products within the two cell types were marked. Electron microscopic autoradiography of toads killed 4 hours after 3H-glucose injection showed that silver grains were associated with accumulations of the respective secretory products in sustentacular and inner mantle cells, and label was found over the cupular trough area, where the bases of the cupulae are attached. These results suggest that the cupular core and sheath may both contain mucopolysaccharide, and the sheath, a sulfated mucopolysaccharide.