ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

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Autoregulation of avian renal plasma flow: contribution of the renal portal system (1991)

Wideman, Robert F.

Springer

Journal of comparative physiology 160 (1991), S. 663-669

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ISSN: 1432-136X

Keywords: Renal hemodynamics ; Autoregulation ; Kidney function ; Chicks

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary A simplified avian kidney model was used to assess renal plasma flow (RPF) at normal (100–110 mmHg) or unilaterally reduced (40–50 mmHg) renal arterial perfusion pressure (RAPP) in domestic fowl with ambient (AMBIENT group) or restricted (RESTRICTED group) renal portal flow. Direct measurement of para-aminohippuric acid (PAH) extraction efficiencies (EPAH) allowed avian RPF to be calculated from the clearance of PAH (CPAH). EPAH was unaffected by RAPP, thereby validating the use of PAH to estimate RPF during experimental hemodynamic manipulations. CPAH and RPF were unaffected by RAPP in the AMBIENT group (“perfect” autoregulation), but decreased significantly compared with contralateral kidney values during reduction of RAPP in the RESTRICTED group. Urine flow and glomerular filtration rates (GFR) were reduced unilaterally along with RAPP, regardless of the portal perfusion status. The renal portal system contributes to overall RPF autoregulation in domestic fowl, helping to maintain constancy of renal blood flow even after RAPP is reduced well below the GFR autoregulatory limit.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00571265

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Sodium excretion rates and renal responses to acute salt loading in the European starling (1989)

Laverty, Gary ; Wideman, Robert F.

Springer

Journal of comparative physiology 159 (1989), S. 401-408

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ISSN: 1432-136X

Keywords: Avian kidney ; Sodium excretion ; Cloacal salt transport ; Salt loading ; Glomerular filtration rate

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary Renal clearance studies were performed in European starlings (Sturnus vulgaris) in order to determine the extent of ureteral sodium excretion under control conditions and during an acute, hyperosmotic salt stress. These experiments also estimated the contribution of the lower intestine (colon and cloaca) to postrenal solute reabsorption by making both cloacal and ureteral urine collections in the same birds. A comparison of ureteral vs cloacal excretion rates found significantly higher sodium (9.09±1.30 vs 1.03±0.38 μEq·kg−1·min−1) and chloride (4.15±0.56 vs 1.00±0.38 μEq·kg−1·min−1) excretion rates during the ureteral collections. Fractional excretion of sodium was also significantly higher during ureteral collections, but this value did not exceed 1% of the filtered sodium load during either collection series. Urine flow rate was significantly higher during cloacal collections, suggesting osmotic back-flux of water across the cloacal wall. Infusion of a 1M NaCl solution resulted in rapid increases in glomerular filtration rate (GFR), urine flow rate, and urine osmolality. Fractional sodium and water reabsorption decreased by 11% and 4%, respectively. Glomerular counts and size distribution profiles, measured by in vivo alcian blue labelling, provided no evidence for a reduction in the number of filtering glomeruli during hyperosmotic saline loading. We conclude that renal sodium excretion rates for the starling are similar to those seen in other avian species and in mammals. These studies also provide direct evidence for postrenal modification of urine in this species, even under conditions of continuous flow. Acute hyperosmotic salt stress can, under some conditions, cause increased rather than decreased GFR, indicating multiple regulatory pathways. Finally, there was no evidence in these studies for glomerular shutdown in response to salt loading.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00692412

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Dietary sodium, glomerular filtration rate autoregulation, and glomerular size distribution profiles in domestic fowl (Gallus gallus) (1990)

Vena, Vincent E. ; Lac, Tri Huynh ; Wideman, Robert F.

Springer

Journal of comparative physiology 160 (1990), S. 7-16

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ISSN: 1432-136X

Keywords: Renal hemodynamics ; Urine concentration ; Kidney function

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary Mammalian glomerular filtration rate (GFR) autoregulation can be impaired by protocols that inhibit tubuloglomrular feedback, such as high sodium intake. Domestic fowl were fed diets containing either high sodium (0.39% Na: High-Na Group) or low sodium (0.03% Na: Low-Na Group). An arterial snare was used to reduce renal arterial perfusion pressure (RAPP) in a stepwise fashion to evaluate GFR autoregulation. Absolute sodium excretion, fractional sodium excretion (FENa), and ambient systemic arterial blood pressure were significantly elevated in the High-Na Group when compared with the Low-Na Group, and pressure natriuresis was abolished by the Low-Na diet. However, GFR autoregulatory profiles were identical in birds fed High-Na and Low-Na diets, suggesting that tubuloglomerular feed-back does not contribute significantly to avian GFR autoregulation. Filtering glomeruli were stained in vivo with alcian blue dye to determine if RAPP-induced reductions in GFR are associated with cessation of filtration (glomerular intermittency) by a portion of the nephron population. RAPP was held below the GFR autoregulatory range (experimental group) or was at ambient systemic arterial pressure (control group) during glomerular staining. Reducing RAPP below the autoregulatory range reduced GFR by 50%, but similar glomerular size distribution profiles were observed for experimental and control groups. These results indicate that sustained glomerular intermittency does not contribute to the decrease in GFR when RAPP is reduced below the autoregulatory range.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00258757

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Microanatomy of the renal cortex in the domestic fowl (1981)

Wideman, Robert F. ; Braun, Eldon J. ; Anderson, Gary L.

New York, NY : Wiley-Blackwell

Journal of Morphology 168 (1981), S. 249-267

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ISSN: 0362-2525

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Two aspects of the avian renal cortical microanatomy previously were unclear. The precise in situ folding patterns and orientations of the nephrons with respect to the other cortical elements had not been demonstrated. It also was not known whether certain nephron segments are supplied exclusively by either the arterial or the portal blood flow. In the present study, a new casting compound was developed to allow selective examination of the cortical components by light microscopy. Cortical nephrons at the surface of the kidney were serially sectioned and reconstructed in order to determine: (a) their relationships to the vasculature and collecting ducts; (b) the location and characteristics of the tubule segments; and (c) the primary and secondary folding patterns of the tubules. The anatomical findings were documented individually and then summarized in a comprehensive diagram of the superficial cortical microanatomy. In addition, an in vivo method was used to determine the extent of portal blood distribution to the nephron segments. It was demonstrated that renal portal blood suffuses all of the segments except for the loops of Henle.

Additional Material: 16 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jmor.1051680302

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5

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Innervation of the parathyroid in the european starling (Sturnus vulgaris) (1980)

Wideman, Robert F.

New York, NY : Wiley-Blackwell

Journal of Morphology 166 (1980), S. 65-80

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ISSN: 0362-2525

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Anatomical studies were conducted to characterize the source, type, and distribution of parathyroid gland innervation in European starlings. Denervation experiments demonstrated that the parathyroid glands and adjacent carotid bodies are innervated by nerve fibers originating in the nodose ganglion of the vagus nerve. In the parathyroid parenchyma, these fibers terminate adjacent to chief cells or near vascular smooth muscle. Vagal fibers also form synapses with catecholamine-containing glomus cells of the carotid body. Blood that first perfuses the carotid body subsequently perfuses the parathyroid parenchyma. These observations suggest that vagal innervation may influence parathyroid function in starlings either through direct chief cell innervation or through alteration of vascular perfusion. A neurohemal relationship also may exist between the carotid body and parathyroids.

Additional Material: 13 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jmor.1051660106

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6

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Maturation of glomerular size distribution profiles in domestic fowl (Gallus gallus) (1989)

Wideman, Robert F.

New York, NY : Wiley-Blackwell

Journal of Morphology 201 (1989), S. 205-213

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ISSN: 0362-2525

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Previous histological evaluations of chick kidneys indicated nephrons continue to develop from embryonic foci for up to 6 weeks after hatching. The present study was conducted using an in vivo alcian blue staining technique to quantify posthatch changes in glomerular numbers and sizes in female domestic fowl at 1, 3, 5, 9, 12, 21, and 30 weeks of age. Changes in glomerular size distributions reflect changes in the heterogeneous nephron populations of avian kidneys. Foci of embryonic tissue were observed at the periphery of renal lobules up to 12 weeks of age. Glomerular numbers increased from 69,800/kidney at 1 week to 586,000/kidney at 12 weeks, with no further significant increase up to 30 weeks (599,000/kidney). The increase in glomerular number per gram kidney weight remained constant as kidney mass increased up to 12 weeks of age, after which the number of glomeruli per gram kidney weight declined significantly as kidney size increased without further addition of new nephrons. Glomerular size distribution profiles were constructed using eleven circumference categories. The peak number of glomeruli fell within the 0.11-0.14 mm category at 1 and 3 weeks; within the 0.15-0.18 mm category at 5, 9, and 12 weeks; and within the 0.19-0.22 mm category at 21 and 30 weeks. One and 3-week-old chicks had no glomeruli within the largest (≥0.35 mm circumference) size categories, and 9-12-week-old birds had significantly fewer glomeruli in these categories than 21-30-week-old birds. These results demonstrate that posthatch renal maturation in domestic fowl involves the ongoing formation of new nephrons up to 12 weeks of age, with subsequent kidney growth (12-30 weeks of age) accomplished by enlargement of existing nephrons (nephron hypertrophy). The cumulative evidence indicates that nephrons destined to develop loops of Henle (mammalian-type) develop first, with shorter (reptilian-type) nephrons developing later as the kidneys enlarge.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jmor.1052010209

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