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At least 55 records · Page 3Linked to original sources
PubMed1997

Pharmacological modulation of electromechanical coupling in the proximal and distal regions of the guinea-pig renal pelvis.

1. The effect of drugs affecting calcium and potassium channels and intracellular calcium handling/release on electromechanical coupling in the smooth muscle of the guinea-pig proximal vs. distal renal pelvis were investigated by using the single sucrose gap method. 2. Spontaneous action potentials discharged from the proximal renal pelvis were bell-shaped, did not show a pronounced plateau and had a small after-hyperpolarization. Spontaneous action potentials from the distal renal pelvis were characterized by a fast depolarization, a pronounced plateau and after-hyperpolarization. 3. Nifedipine (1 microM) suppressed action potentials in both regions of the renal pelvis. A submaximally effective concentration of nifedipine (50 nM) shortened action potential duration and reduced contractility in both regions of the renal pelvis. On the other hand Bay K 8644 (1 microM) markedly prolonged the duration of the action potential and increased contractility in both regions of the renal pelvis. 4. Tetraethylammonium (0.5 mM) markedly prolonged the action potential duration and contraction in the distal renal pelvis without affecting action potentials in the proximal renal pelvis. Similar effects were produced by a slightly higher concentration of tetraethylammonium (2 mM) in the proximal renal pelvis. 5. Charybdotoxin (30 nM) markedly prolonged the duration of action potential and increased and prolonged the contraction in both the proximal and distal renal pelvis. 6. 4-aminopyridine (1 mM) selectively increased the frequency of action potentials in the distal renal pelvis without affecting other parameters of the action potential nor contractility. 4-aminopyridine had no effect in the proximal renal pelvis. 7. The inhibitor of sarcoplasmic reticulum Ca-ATPase, cyclopiazonic acid (10 microM) transiently increased the frequency of action potentials in both regions of the renal pelvis; CPA markedly delayed the repolarizing phase of the action potential in both the proximal and distal renal pelvis and, in parallel, increased contractility. 8. We conclude that action potentials generated from the proximal and distal regions of the guinea-pig renal pelvis are evenly dependent upon the availability of L-type Ca channels; that Ca-dependent maxi K channels provide a major contribution to the repolarization of action potentials in both regions of the renal pelvis, thus regulating duration/intensity of Ca influx and contraction; that release of Ca from the internal store is not important in providing activator Ca for contraction but regulates duration of the action potential and may be involved in setting the frequency of discharge of pacemaker cells.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMedDate not supplied

[Meaning of assimilation pelvis according to Kirchhoff in modern obstetrics].

OBJECTIVE: To what extent is the cesarean section indication "arrest of labour" due to pathological forms of the pelvis and what is the meaning of the assimilation pelvis in modern obstetrics. PATIENTS: NMR-pelvimetries were performed in 166 post partum women from June 1993 to August 1995. The patients were divided into 4 groups. Group 1: patients who had had cesarean section owing to arrest of labour (n = 56), group 2: patients who had had cesarean section due to breech presentation (n = 20), group 3: patients who had had cesarean section owing to another indication (threatening fetal asphyxia, multiple pregnancy, premature delivery, placental abruption, gestosis, n = 40), group 4: patients who had a spontaneous delivery (control group, n = 50). After analysing the NMR pictures all the pelves were alloted to one of the case studies according to their pelvic form. The diagnosis "assimilation pelvis" was made according to the criteria of Kirchhoff (1949). The four groups were compared and analysed. RESULTS: In group 1 an assimilation pelvis was found in 61%. The obstetrically most unfavourable canal pelvis occurred most frequently, amounting to 29%. In only 9% we found a contracted pelvis. In group 2 the proportion of the assimilation pelvis was even higher, rising to 65%. Only 35% of all pelves had a normal shape. In group 3 we found an assimilation pelvis in 50% of all cases. 66% of all patients with spontaneous delivery had a normal pelvis. An assimilation pelvis was found in 34%. In these cases duration of labour was prolonged by 4 hours on average (mean value: 9.5 hours). CONCLUSIONS: Due to its frequency in our days the assimilation pelvis plays a major obstetrical role. This is true in particular when there is a pathological course of labour. From this results that pelvic parameters other than the conjugata vera will be of diagnostic importance, especially those parameters which are able to characterise the assimilation pelvis with its high promontory, the steepness of the pelvic inlet, the lengthening of the birth canal and the decrease of the hollow of the sacrum. We take the view that the angle of the pelvic inlet, the pelvic inclination and the direct length of the pelvis are of outstanding importance.

Breech Presentation↗
PubMed1981

[The importance of the long pelvis in clinical practice and medical education (author's transl)].

The importance of the long pelvis with lumbo-sacral assimilation in obstetrics is evaluated. 111 x-rays of the pelvis in cases with abnormal deliveries were evaluated and compared to the clinical data. The incidence of the long pelvis was not increased in the total group, nor in the 100 cases with abnormal deliveries. A long pelvis was present in 30.2% of the 43 breech presentations. In 4 cases with a funnel pelvis vaginal delivery occurred without difficulty. In 42 posterior vertex presentation the long pelvis appears to have a pathogenetic importance regarding the primary posterior position. The further course of the delivery was not influenced by the long pelvis. In 7 cases of low transverse arrest, 4 had a long pelvis but only 1 had a funnel pelvis to explain this abnormal position. In summary, the long pelvis even in its most severe form, the funnel pelvis, does not block the adaptation processes in the lesser pelvis. The changes in the pelvic inlet due to the lumbo-sacral assimilation have an etiologic importance on the initial presentation at the inlet such as breech presentation, military vertex presentation, brow presentation, or Roederers anomaly. However, no prognostic value for the mechanism of the delivery can be derived from the initial presentation. The delivery dose not depend on the long pelvis but on the malpresentation when delivery becomes necessary.

Breech Presentation↗
PubMed1994

Effects of intrinsic prostaglandins on the spontaneous contractile and electrical activity of the proximal renal pelvis of the guinea-pig.

1. The effects of blocking prostaglandin biosynthesis with indomethacin on the spontaneous electrical and contractile activity recorded in smooth muscle strips of the guinea-pig renal pelvis were examined using standard tension and membrane potential recording techniques. 2. Circumferentially cut strips of proximal renal pelvis contracted more frequently (4.5 +/- 0.2 min-1) than strips cut from the mid region (1.3 +/- 0.2; P < 0.05, n = 5) of the renal pelvis. 3. Indomethacin (1 nM-10 microM) reduced the amplitude and frequency of the contractions of the renal pelvis in a concentration- and time-dependent manner. Contractions were completely abolished in the presence of 30 microM indomethacin. 4. After indomethacin blockade, activation of prostaglandin F2 alpha (PGF2 alpha) receptors with dinoprost (1-100 nM) restored the amplitude and frequency of the spontaneous contractions of renal pelvis. Higher concentrations of dinoprost (> 100 nM-3 microM) increased the contraction amplitude of the proximal and mid renal pelvis 1.9 and 1.6 times respectively. The contraction frequency of the mid renal pelvis, but not the proximal pelvis, was also raised above its pre-indomethacin frequency. 5. The spontaneous electrical activity recorded in proximal strips of the renal pelvis was designated to come from three cell types: (i), pacemaker cells (10% of cells recorded), with simple action potentials comprising relatively slow rising and repolarizing phases triggered on top of a slowly-developing pre-potential; (ii), driven cells (75% of cells), with complex action potentials comprising a rapid initial spike, followed by a period of membrane oscillation and a plateau of 0.2-2 s duration; and (iii), intermediate cells (15%) which fired action potentials with an initial rapid and a long plateau phase. 6. Indomethacin (10-30 micro M) decreased the amplitude and frequency of the action potentials recorded in driven and intermediate cells. The membrane potential of these cells also depolarized 5mV to-51.2 +/-2.6mV (n=5).7. Dinoprost (300 nM-1.5 micro M) increased the rate of action potential discharge, without affecting the membrane potential of driven cells previously exposed to indomethacin (30 micro M).8. These data suggest that the endogenous release of prostaglandins is necessary for the in vitro spontaneous contractile activity recorded in the guinea-pig renal pelvis. Blockade of the synthesis of these prostaglandins appears either to modify the ability of the driven regions of the renal pelvis to fire action potentials or to reduce the coupling of these driven regions to their pacemaker cells.

Action Potentials↗
PubMed1997

In utero progression of isolated renal pelvis dilation.

The objective of this study to determine the risk of in uteroprogression of renal pelvis dilation when detected on antenatal ultrasound examination. We reviewed 230 fetuses with evidence of renal pelvis dilation. At least one exam was subsequently performed prior to delivery in all cases. Renal pelvis dilation was defined as an anterior-posterior renal pelvis measurement > 4 mm at < 32 weeks' and > 7 mm at > or = 32 weeks' gestation. Hydronephrosis was considered to be present when the renal pelvis measured +10 mm independent of gestational age. Multiple gestations and fetuses with additional congenital anomalies were excluded. The mean gestational age at diagnosis was 24 weeks. Renal pelvis dilation progressed to hydronephrosis in a total of 10.9% (25 of 230) of fetuses. There was a 3.3% chance of unilateral renal pelvis dilation progressing to hydronephrosis versus 26.0% in bilateral dilation (OR 10.4 [95% Cl 3.5-33.3]). Of those fetuses with progression, 80% had bilateral dilation (p < 0.0001). There was no difference in progression between right and left kidneys. Additionally, gender, gestational age at diagnosis and delivery, and birth weight did not differ between those fetuses with and without progression. The hydronephrosis in 7 of 25 (28%) regressed to pyelectasis on a subsequent ultrasound exam. Thus, the overall rate of progression of renal pelvis dilation to persistent hydronephrosis was 7.8% (18 of 230). In conclusion, the risk of isolated renal pelvis dilation progressing to hydronephrosis is low. Although bilateral pelvis dilation carries a higher risk for progression, no fetus in our study required in utero intervention. A follow up scan prior to delivery may be considered to identify those fetuses who will require postpartum intervention.

Adult↗
PubMed1987

Movement of the human pelvis and displacement of related anatomical landmarks on the body surface.

Anatomical landmarks on the body surface can be measured with high accuracy by using rasterstereography and surface curvature analysis. The present study shows that the lumbar dimples can be localized with a statistical error of about 1 mm. It is generally assumed that the dimples are in close relation to the pelvis (in particular to the PSISs) and may thus be taken as indicators for pelvis movements. By introducing an artificial pelvis tilt of up to +/- 10 degrees this relation was examined. In fact, a nearly perfect correlation (r approximately equal to 0.99) between landmark and pelvis movements was observed. Asymmetries of pelvis motion due to scoliotic deformity were not observed. There was, however, a systematic lag of the dimple movements, resulting in a displacement of the dimples of up to +/- 1.5 mm relative to the pelvis (for +/- 10 degrees pelvis tilt). Either a soft tissue effect or a torsion of the pelvis may be responsible for this behaviour. The theory of pelvis torsion is confirmed by the fact that the orientation of the back surface at the locus of the dimples reveals a corresponding torsion of similar magnitude and sign. A torsion angle of about +/- 1.5 degrees in either sacro-iliac joint is sufficient to explain the observed dimple lag and the surface torsion. An independent measurement (e.g. using roentgenphotogrammetry) would be desirable to further validate this theory. According to our measurements the dimples of the PSISs cannot be taken as exact indicators for orientation and movement of the pelvis.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed2002

Three-dimensional angular kinematics of the lumbar spine and pelvis during running.

The objective of this study were to: (i) describe the typical three-dimensional (3D) angular kinematics of the lumbar spine and pelvis during running and; (ii) assess whether the movements of the lumbar spine and pelvis during running are coordinated. A cohort of 20 non-injured male runners who usually ran >20 km/week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m/second. Reflective markers were placed over anatomical landmarks of the thoraco-lumbar spine and pelvis. Data were captured using a VICON motion analysis system. The lumbar spine and pelvis both displayed complex 3D angular kinematic patterns during running. High correlations were found for the comparisons of flexion-extension of the lumbar spine with anterior-posterior tilt of the pelvis (r=-0.84) and lateral bend of the lumbar spine with obliquity of the pelvis (r=-0.75). However, a poor correlation was found for the comparison of axial rotation of the lumbar spine with axial rotation of the pelvis (r=0.37). A phase difference of 21% of the running cycle was evident between axial rotation of the lumbar spine and pelvis. The identified coordinated kinematic patterns of the lumbar spine and pelvis during running serve as a basis for future investigations exploring the relationship between atypical kinematic patterns and injury.

Adult↗
PubMed1995

Left renal pelvis of male neonates is predisposed to dilatation.

Dilatation of the renal pelvis has been observed as an ultrasonographic finding of ureteral reflux as well as hydronephrosis. However, little information is available on the prevalence of renal pelvis at dilatation in neonates. We measured the inner pelvis dimension of the kidneys in 511 apparently healthy neonates (279 boys and 232 girls) using an ultrasound scanner to determine the prevalence of renal pelvis dilatation. Ninety per cent of the neonates had an inner dimension of both renal pelvises below 5 mm. The prevalence of left renal pelvis dilatation of 5 mm or more was significantly higher in the boys than in the girls, 25 (9%) compared to 5 (2%). In contrast, no significant difference was found in the prevalence of right renal pelvis dilatation between the sexes. In the boys, the prevalence of renal pelvis dilatation of 6 mm or more was significantly higher on the left side than on the right. Moreover, the left renal pelvis dilatation of the male neonates had a tendency to persist at 1 month of age. These findings suggest that the left renal pelvis of the baby boy may be predisposed to dilatation.

Chi-Square Distribution↗
PubMed2005

Diuresis and natriuresis caused by activation of VR1-positive sensory nerves in renal pelvis of rats.

To test the hypothesis that activation of the vanilloid receptor 1 (VR1) expressed in sensory nerves innervating the renal pelvis leads to diuresis and natriuresis, a selective VR1 receptor agonist, capsaicin (2.4 nmol), or vehicle was perfused intravenously or into the left renal pelvis of anesthetized rats at a rate without changing renal perfusion pressure. Mean arterial pressure was not altered by capsaicin administered intravenously or into the renal pelvis. Capsaicin perfusion into the left renal pelvis but not intravenously caused significant increases in urine flow rate and urinary sodium excretion bilaterally in a dose-dependent manner, which were abolished by capsazepine, a selective VR1 receptor antagonist, given ipsilaterally to the renal pelvis or by ipsilateral renal denervation. Capsaicin given intravenously or into the left renal pelvis increased plasma calcitonin gene-related peptide levels to the same extent. Increased plasma calcitonin gene-related peptide levels induced by capsaicin (68.9+/-2.8 pg/mL) perfusion into the renal pelvis was prevented either by capsazepine (22.5+/-10.1 pg/mL) given ipsilaterally into the renal pelvis or by ipsilateral renal denervation (25.9+/-2.3 pg/mL). Taken together, our data show that unilateral activation of VR1-positive sensory nerves innervating the renal pelvis leads to bilateral diuresis and natriuresis via a mechanism that is independent of plasma calcitonin gene-related peptide levels. These data suggest that VR1-positive sensory nerves in the kidney enhance renal excretory function, a mechanism that may be critically involved in sodium and fluid homeostasis.

Animals↗
PubMed1984

Examination of transepithelial exchange of water and solute in the rat renal pelvis.

Severance of the ureter beyond the renal papilla causes a fall in urinary osmolality, which suggests that exchange of water or solute between urine and renal parenchyma normally occurs in the intact renal pelvis. We examined water and solute flux in the renal pelvis with micropuncture and microcatheterization techniques. Four groups of antidiuretic rats were studied. Group I (n = 17) underwent micropuncture through the intact contracting ureter. Urine samples were obtained at the papillary tip, and in the pelvis beside the base of the extrarenal papilla. Urinary osmolality at the base, 880 +/- 97 mosmol/kg H2O (mean +/- SE), was less than that at the tip, 1,425 +/- 104 mosmol/kg H2O (P less than 0.005). In group II (n = 24), samples were analyzed for inulin and osmolality. In 15 rats (group IIA), comparison was made between base and tip samples. In the other nine animals (group IIB), comparisons were made among base, tip, and bladder samples and urea was also measured. In group II (A and B combined) urine-to-plasma (U/P) osmolality was lower at the base, 4.31 +/- 0.27, than at the tip, 6.08 +/- 0.23 (P less than 0.001), and U/P inulin was lower at the base, 192 +/- 25, than at the tip, 306 +/- 16 (P less than 0.001). In group IIB, the bladder urine had a lower U/P osmolality, 5.27 +/- 0.25, than the tip, 6.01 +/- 0.31 (P less than 0.02). The U/P urea was 59 +/- 10.6 (base), 98 +/- 9.4 (tip) (base vs. tip, P less than 0.05), and 81 +/- 6.5 (bladder, P less than 0.005, compared with tip). In group III (n = 8), samples were obtained by microcatheter from the fornices, the deepest intrarenal extensions of the pelvis, and compared with samples at the tip. Urinary osmolality was lower in the fornix, 646 +/- 106 mosmol/kg H2O, than at the tip, 1,296 +/- 99 mosmol/kg H2O (P less than 0.001). Similarly, U/P inulin was lower in the fornix, 48 +/- 14, than at the tip, 128 +/- 12 (P less than 0.001). The lower U/P inulin in the pelvic urine is the result of either the addition of fluid to the pelvis, or the backleak of inulin across the epithelium lining the pelvis. To verify that the pelvic epithelium was impermeable to inulin, in group IVA (n = 4) the left renal pelvis was superfused with a solution of chemical inulin. Cumulative absorption of inulin from the left kidney was 0.15 +/- 0.08% of that superfused. Using [14C]inulin in group IVB (n= 3), similar results were obtained (0.05 +/- 0.02%). These findings indicate that in the renal pelvis, fluid is added to urine after it emerges from the collecting ducts. We suggest that reflux of hyperosmotic urine over the renal papilla creates a transepithelial gradient for the flux of water into the pelvis. A model that incorporates diffusive and convective forces for water and solute transport is proposed to account for these findings.

Animals↗
PubMed1995

CGRP inhibition of electromechanical coupling in the guinea-pig isolated renal pelvis.

We aimed at studying the mechanism(s) of the inhibitory effect exerted by calcitonin gene-related peptide (CGRP) on the spontaneous activity of the guinea-pig isolated renal pelvis. In organ bath experiments, CGRP (1-100 nM) produced a concentration-dependent (EC50 8 nM) partial inhibition (Emax about 35% inhibition of motility index) of spontaneous contractions. The potassium (K) channel opener, cromakalim (3-10 microM) promptly suppressed the spontaneous contractions in a glibenclamide-(10 microM) sensitive manner. Glibenclamide (10 microM) did not affect the inhibitory action of CGRP. The calcium (Ca) channel agonist, Bay K 8644 (1 microM), markedly enhanced the spontaneous activity of the renal pelvis and reduced the inhibitory effect of CGRP. The protein kinase A inhibitors Rp-cAMPS (300 microM), H8 (100 microM) and H89 (10 microM), and the blockers of intracellular Ca handling by sarcoplasmic reticulum, ryanodine (100 microM) and thapsigargin (1 microM) did not affect the response to CGRP. The response to CGRP was likewise unaffected by the nitric oxide synthase inhibitor, L-nitroarginine (30 microM) and by the protein kinase G inhibitor, KT5823 (3 microM). Furthermore, the inhibitory action of CGRP was not modified by lowering the extracellular concentration of K (from 5.9 to 1.2 mM) nor by increasing (from 2.5 to 3.75 mM) or decreasing (from 2.5 to 0.25 mM) the extracellular Ca concentration. Replacement of 80% glucose with 2-deoxyglucose (2-DOG) reduced the amplitude of spontaneous contractions, both in the absence and presence of 10 microM glibenclamide. In the presence of 2-DOG, the inhibitory action of CGRP was enhanced at a similar extent, either in the absence or presence of glibenclamide. In sucrose gap, the effect of CGRP (0.1 microM for 5 min) was separately analyzed in the proximal (close to the kidney) and distal (close to the ureter) regions of the renal pelvis. Both preparations discharged spontaneous (pacemaker) action potentials having different shape, duration and frequently. CGRP had no effect on pacemaker potentials in the proximal renal pelvis while producing about 30% reduction of the frequency of pacemaker potentials and motility index in the distal renal pelvis. Cromakalim (3 microM) abolished pacemaker potentials in both regions of the renal pelvis. In conjunction with the results of previous studies in the guinea-pig ureter, the present findings document the existence of remarkable regional differences in the effector mechanisms initiated by CGRP receptor occupancy in the guinea-pig pyeloureteral tract. CGRP appears to be inherently unable to activate glibenclamide-sensitive K channels in the guinea-pig renal pelvis, a mechanism which is central for its ability to suppress latent pacemakers in the ureter. Within the renal pelvis, the sensitivity to the inhibitory effect of CGRP appears in the more distal region, from which an 'ureter-like' action potential is recorded.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2001

Developmental changes in the biochemical and functional properties of endothelin receptors in rabbit renal pelvis.

OBJECTIVE: To examine the effect of age on the biochemical and functional properties, and regional distribution of endothelin (ET) receptors in the rabbit renal pelvis. MATERIALS AND METHODS: The properties of ET receptors in 6-week-old and 6-month-old male rabbit renal pelves were examined using isolated muscle-bath and radioligand receptor-binding techniques. RESULTS: ET-1 caused a significant increase in the contractile force in muscle strips from all regions of the renal pelvis from both age groups, with the following rank order: upper=middle>lower. The magnitude of the ET-1-induced contractile responses were similar in the lower pelvic regions in both ages, but the responses in the upper and middle regions were significantly greater in younger rabbits. ET-1 increased the frequency of spontaneous activity in a concentration-dependent manner in the upper and middle pelvic regions in both age groups, with significantly smaller ED50 values in the younger than in the older rabbits. In both age groups the lower pelvic region lacked spontaneous activity. The density of total ET receptors was higher in the upper and middle regions of the renal pelvis than in the lower renal pelvis of both ages, with the density in the upper and middle regions being greater in older than in younger rabbits. In all regions, ET subtype selective compounds inhibited [125I]ET-1, binding consistent with the predominance of the ETA receptor subtype, except in the lower region of the older rabbits, in which the densities of ETA and ETB subtypes were similar. In all regions, the younger renal pelvis contained a higher proportion of ETA receptors than in older tissues. Light microscopic autoradiographic data indicated the presence of ETA and ETB receptors in smooth muscle and epithelial cells, respectively. CONCLUSION: These data indicate the presence of regional differences in the density of ET receptors and in the contractile responses to ET-1 in rabbit renal pelvis, and that although older rabbit renal pelvis contains more total ET receptors than younger renal pelvis, the latter had a higher portion of the ETA receptor subtype and the younger tissues were more responsive to ET-1.

Aging↗
PubMed2004

Influence of pelvis rotation styles on baseball pitching mechanics.

Efficient, sequential timing is essential for upper level pitching. Interestingly, pitchers vary considerably in timing related elements of pitching style including pelvis rotation, arm cocking, stride leg behaviour, and pitch delivery time. The purpose of this study was to determine whether relationships exist among these elements by examining the overall style of pitchers exhibiting different pelvis rotation patterns. Pitching styles were defined by pelvis orientation at the instant of stride foot contact. Pitchers demonstrating a pelvis orientation greater than 30 degrees were designated as 'early rotators', while pitchers demonstrating a pelvis orientation less than 30 degrees were designated as 'late rotators'. Kinematic and temporal differences were associated with the two styles. During the arm cocking phase, early rotators showed significantly greater shoulder external rotation at the instant of stride foot contact, earlier occurrence of maximum pelvis rotation angular velocity, and shorter time taken to complete the phase. However, by the instant of maximum shoulder external rotation, early and late rotators appeared remarkably similar as no significant difference occurred in pelvis and arm orientations. Therefore, it appears that early and late rotators used different methods to achieve similar results, including throwing velocity. Significant differences in throwing arm kinetics were also found for 10 of the 11 measures in the study. As the pelvis assumed a more open position at stride foot contact, maximum kinetic values were found to both decrease in magnitude and occur at an earlier time within the pitch.

Adolescent↗