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At least 145 records · Page 8Linked to original sources
PubMed2005

Characterisation of opioid receptors involved in modulating circular and longitudinal muscle contraction in the rat ileum.

1. The aim of the present investigation was to characterise the opioid receptor subtypes present in the rat ileum using a method that detects drug action on the enteric nerves innervating the circular and longitudinal muscles. 2. Neurogenic contractions were reversibly inhibited by morphine (circular muscle pEC50, 6.43+/-0.17, Emax 81.7+/-5.0%; longitudinal muscle pEC50, 6.65+/-0.27, Emax 59.7+/-7.8%), the mu-opioid receptor-selective agonist, DAMGO ([D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin acetate) (circular pEC50, 7.85+/-0.04, Emax 97.8+/-3.6%; longitudinal pEC50, 7.35+/-0.09, Emax 56.0+/-6.1%), the delta-selective agonist DADLE ([D-Ala2,D-Leu5]enkephalin acetate) (circular pEC50, 7.41+/-0.17, Emax, 93.3+/-8.4%; longitudinal pEC50, 6.31+/-0.07, Emax 66.5+/-5.2%) and the kappa-selective agonist U 50488H (trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide methanesulphonate) (circular pEC50, 5.91+/-0.41, Emax, 83.5+/-26.8%; longitudinal pEC50, 5.60+/-0.08, Emax 74.3+/-7.2%). Agonist potencies were generally within expected ranges for activity at the subtype for which they are selective, except for U 50488H, which was less potent than expected. 3. The mu and delta receptor-selective antagonists, CTAP (H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2) and naltrindole, caused progressive, parallel rightward shifts in the DAMGO and DADLE curves, respectively. Analysis indicated conformity to theoretical simple competitive antagonist behaviour. U 50488H effects were insensitive to the kappa-selective antagonist, n-BNI. A high concentration (1 microM) of naltrexone caused apparent potentiation of U 50488H effects. 4. CTAP pK(B) estimates were consistent with previously reported values for mu receptor antagonism (circular 7.84+/-0.17, longitudinal 7.64+/-0.35). However, the naltrindole pK(B) estimates indicated lower antagonist potency than expected (circular 8.22+/-0.23, longitudinal 8.53+/-0.35). 5. It is concluded that mu and possibly atypical delta receptors (but not kappa receptors) mediate inhibition of contraction in this model. Nonopioid actions of U 50488H are probably responsible for the inhibitory effects seen with this compound.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed2003

Perfusion bioreactor for vascular tissue engineering with capacities for longitudinal stretch.

Arterial growth during embryonic vascular development is associated with longitudinal strain. The longitudinal strain is an important element of the embryonic vascular mechanical environment (EVME). Thus, a perfusion bioreactor for vascular tissue engineered constructs must include the functional capacity for longitudinal strain. To accomplish this goal, a perfusion bioreactor with the capacity for longitudinal strain was developed. The bioreactor includes two media perfusion systems: one for the inside perfusion and one for the outside perfusion of the cardiovascular engineered tubular construct (CETC). The watertight perfusion chamber allows periodic changing of longitudinal strain of the construct during mechanical conditioning. The range of the longitudinal strain is 0% to 200%. The biomechanical properties of the CETC are controlled by a pressure transducer and a digital TV camera. The pressure transducer and TV camera are connected to a computer. This allows the recording of a relationship between the radius of the VTEG and pressure in both static and dynamic regimens. This bioreactor can perform biomechanical conditioning with longitudinal strain.

Animals↗
PubMed1977

Interaction between longitudinal and circular muscle in intestine of cat.

1. Slow waves recorded from isolated longitudinal muscle averaged 13 mV and had slow rate of rise (0.04 V/sec) whereas when recorded from intact segments the amplitude averaged 27 mV and the rate of rise was more rapid (0.09 V/sec), often with a notch between the initial peak and the plateau. Membrane potentials of longitudinal muscle were similar in isolated and intact preparations (- 66 mV). Resting potentials of circular muscle averaged - 67 mV.2. Small bundles of circular muscle tested in the double sucrose gap produced activity, either spontaneously or in response to stimulation, which fell into three categories: fast spikes (50-200 msec duration), slow spikes (1-5 sec duration), and small graded responses. The duration of fast spikes could be increased severalfold by the addition of TEA; the graded responses were converted to full-sized spikes by TEA.3. Treatment of circular muscle with Ca-free Krebs solution eliminated spikes, and in intact preparations reduced the amplitude and rate of rise of slow waves and eliminated the notch on slow waves.4. Current-voltage curves of longitudinal muscle show delayed rectification in the depolarizing quadrant; similar curves of circular muscle show anomalous rectification, i.e. a region where a very small current causes a large voltage change.5. Non-polarized electrotonic coupling between longitudinal and circular layers indicates low-resistance pathways. Apparent space constants of longitudinal muscle are greater when attached to circular muscle than when isolated.6. It is concluded that small slow potentials originate rhythmically in longitudinal muscle, that these spread passively to circular muscle where a regenerative amplification occurs which depends on Ca conductance and the amplified slow waves spread back to the longitudinal layer. In the intact intestine pacemaking is, therefore, separate from propagation and the circular muscle provides the bulk of depolarizing current for propagation.

Action Potentials↗
PubMed2000

Power flow in coupled bending and longitudinal waves in beams

In complex structures, curvature and impedance discontinuities (e.g., junctions) couple bending and longitudinal waves. Propagation losses for longitudinal waves are often much less than losses for bending waves, and damping treatments often less effective on longitudinal waves. When the dissipation in longitudinal waves is less than that on bending waves, longitudinal waves can provide an efficient means of power flow between bending waves generated at one location and bending waves that are a source of acoustic radiation at another location. In order to design and locate effective treatments, knowledge of the power flow in longitudinal as well as bending waves is required. The measurement of power in both bending and longitudinal waves when both waves are present is demonstrated. Measurements conducted on a straight beam and a T-beam are compared to predictions obtained using finite element methods. The effect of coupling between waves at the junction in a T-beam is illustrated using results from measurements of power flow.

Journal Article↗
PubMed1992

Outward currents in longitudinal colonic muscle cells contribute to spiking electrical behavior.

Electrical events in longitudinal and circular muscles of the colon are different. Longitudinal muscles generate action potentials superimposed upon small depolarizations termed myenteric potential oscillations and circular muscles generate slow wave events that persist for several seconds. Differences between circular and longitudinal muscles may be related to the potassium channels these cells express. We have studied Ca(2+)-dependent and voltage-dependent K currents of isolated longitudinal cells with the whole cell patch-clamp technique. Test depolarizations positive to -40 mV yielded a transient inward current followed by a large sustained outward current. Blockade of the inward Ca2+ current reduced the amplitude of the outward current. Outward current was also reduced by tetraethylammonium (TEA; 1 mM), suggesting that a component of the outward current is Ca2+ dependent. After blockade of the Ca(2+)-dependent outward current, a voltage- and time-dependent component of outward current remained. The activation and inactivation properties and sensitivity to TEA and 4-aminopyridine (4-AP) were characterized. The voltage-dependent outward current in longitudinal cells had different properties than the voltage-dependent K currents in circular muscle cells (i.e., more negative inactivation, less sensitivity to 4-AP). TEA (1-5 mM) increased the amplitude and frequency of action potentials in intact longitudinal muscles; 4-AP (1 mM) had little effect on electrical activity of longitudinal muscles. The data suggest that differences in electrical behavior of the 2 muscle layers may be related to the expression of different species of K channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1983

Electrical activity of longitudinal and circular muscle during peristalsis.

Action potentials were recorded simultaneously from the longitudinal and circular muscle layers of the guinea pig isolated small intestine. Both the graded reflex of the longitudinal muscle and the peristaltic reflex proper could be evoked by raising the intraluminal pressure. At low intraluminal pressures, intervals between spike bursts of the circular muscle were longer than those of the longitudinal muscle. The higher the intraluminal pressure, the shorter became the intervals between spike bursts in the circular muscle, until both muscle layers showed synchronous discharge of action potentials. Tetrodotoxin (100 nM) abolished the excitation of both circular and longitudinal muscles produced by raising intraluminal pressure. Hexamethonium (280 microM) abolished excitation of the circular muscle but not that of the longitudinal muscle. Atropine (100 nM) reduced the excitatory effects of raising pressure on both muscle layers but did not abolish them. The atropine-resistant excitation of the circular, but not the longitudinal, muscle was reversibly blocked by exposure to substance P (100-500 nM). Chymotrypsin (200 micrograms/ml) reversibly abolished the atropine-resistant excitation of the circular muscle. It was concluded that during peristalsis both longitudinal and circular muscle layers are activated synchronously; muscle activation during peristalsis is not entirely cholinergic but may involve in addition a substance P-like peptide.

Action Potentials↗
PubMed1987

Differential effects of [Gln4]neurotensin on circular and longitudinal muscle of dog ileum in vitro.

We studied the effects of neurotensin analogue [Gln4]-neurotensin on isolated dog ileal longitudinal and circular muscle strips. [Gln4]neurotensin stimulated the spontaneous contractile activity of the circular muscle but inhibited that of the longitudinal muscle in a dose-dependent fashion. Hexamethonium had no effect on the spontaneous longitudinal or circular muscle contractile activity. Atropine and tetrodotoxin (TTX) both inhibited the longitudinal muscle. Atropine had no effect on the circular muscle, but TTX stimulated it. The effects of [Gln4]neurotensin on the circular muscle were reduced but not completely abolished by atropine. The inhibition of the longitudinal muscle by [Gln4]neurotensin was not reduced by any of the above antagonists but was enhanced by atropine. Electrical field stimulation (10 Hz, 100 mA) stimulated the longitudinal muscle and inhibited or stimulated the circular muscle depending on the pulse width of the stimulus. These effects were unaffected by [Gln4]neurotensin. We conclude that [Gln4]neurotensin has differential effects on isolated muscle strips of the two muscle layers in the dog ileum. It stimulates the circular muscle partially through cholinergic nerves at preganglionic sites and partially through a direct myogenic effect. [Gln4]neurotensin inhibits the spontaneous activity of the longitudinal muscle presumably by reducing the excitability of cholinergic nerves at postganglionic sites.

Animals↗
PubMed1991

Identification of longitudinal muscle activity in opossum lower esophageal sphincter.

The aim of this study was to characterize lower esophageal sphincter (LES) longitudinal muscle contraction during changes in LES pressure in opossums. LES pressure was used as a marker of LES circular muscle contraction. Longitudinal muscle contraction was measured by strain gauge transducers. For precise placement of the strain gauge on the LES, the high-pressure zone was identified using a manometric-laser illumination technique. Measurements were made during 1) spontaneous LES pressure fluctuations, 2) LES pressure changes induced by pharmacological agents, and 3) LES relaxation induced by vagal nerve stimulation. These studies show that 1) spontaneous LES pressure fluctuations correlated with spontaneous changes in LES longitudinal muscle contraction; 2) pharmacologically induced contraction and relaxation of LES pressure correlated with contraction and relaxation of LES longitudinal muscle, respectively; 3) a close temporal relationship existed between changes in LES longitudinal muscle contraction and LES pressure that occurred spontaneously or were induced pharmacologically; and 4) vagal stimulation caused LES longitudinal muscle contraction and LES pressure relaxation. We propose that LES longitudinal muscle may play a role in the modulation of intraluminal LES pressure.

Animals↗
PubMed1993

Gastrointestinal longitudinal muscle contractions.

The patterns of longitudinal muscle contractions of the stomach and the small intestine and their relationship with circular muscle contractions during the fasting and the fed state were investigated in conscious dogs. In the stomach, the longitudinal muscle contracted in a 1:1 relationship with the circular muscle contractions. There was no significant difference between the frequency, duration, and time of onset of gastric longitudinal and circular muscle contractions, and their amplitudes were significantly correlated with each other. In the small intestine when the circular muscle contracted, the longitudinal muscle exhibited passive elongation during the fasting and the fed state. There was no significant difference between the onset, duration, and frequency of small intestinal circular muscle contractions and the passive longitudinal muscle elongations; their amplitudes were strongly correlated with each other. During a circular muscle giant migrating contraction, the longitudinal muscle exhibited a monophasic contraction, initially a contraction followed by passive elongation or a pure passive elongation. During a retrograde giant contraction, the longitudinal muscle exhibited only a pure monophasic contraction or a contraction-elongation complex. These data suggest that the enteric nerves in the small intestine innervate the two muscle layers in a reciprocal fashion and those in the stomach in a complementary fashion.

Animals↗
PubMed2006

Longitudinal movements and resulting shear strain of the arterial wall.

There has been little interest in the longitudinal movement of the arterial wall. It has been assumed that this movement is negligible compared with the diameter change. Using a new high-resolution noninvasive ultrasonic method, we measured longitudinal movements and diameter change of the common carotid artery of 10 healthy humans. During the cardiac cycle, a distinct bidirectional longitudinal movement of the intima-media complex could be observed in all the subjects. An antegrade longitudinal movement, i.e., in the direction of blood flow, in early systole [0.39 mm (SD 0.26)] was followed by a retrograde longitudinal movement, i.e., in the direction opposite blood flow [-0.52 mm (SD 0.27)], later in systole and a second antegrade longitudinal movement [0.41 mm (SD 0.33)] in diastole. The corresponding diameter change was 0.65 mm (SD 0.19). The adventitial region showed the same basic pattern of longitudinal movement; however, the magnitude of the movements was smaller than that of the intima-media complex, thereby introducing shear strain and, thus, shear stress within the wall [maximum shear strain between the intima-media complex and the adventitial region was 0.36 rad (SD 0.26). These phenomena have not previously been described. Measurements were also performed on the abdominal aorta (n = 3) and brachial (n = 3) and popliteal (n = 3) arteries. Our new information seems to be of fundamental importance for further study and evaluation of vascular biology and hemodynamics and, thus, for study of atherosclerosis and vascular diseases.

Adult↗
PubMed2001

Roundabout signalling, cell contact and trophic support confine longitudinal glia and axons in the Drosophila CNS.

Contrary to our knowledge of the genetic control of midline crossing, the mechanisms that generate and maintain the longitudinal axon pathways of the Drosophila CNS are largely unknown. The longitudinal pathways are formed by ipsilateral pioneer axons and the longitudinal glia. The longitudinal glia dictate these axonal trajectories and provide trophic support to later projecting follower neurons. Follower interneuron axons cross the midline once and join these pathways to form the longitudinal connectives. Once on the contralateral side, longitudinal axons are repelled from recrossing the midline by the midline repulsive signal Slit and its axonal receptor Roundabout. We show that longitudinal glia also transiently express roundabout, which halts their ventral migration short of the midline. Once in contact with axons, glia cease to express roundabout and become dependent on neurons for their survival. Trophic support and cell-cell contact restrict glial movement and axonal trajectories. The significance of this relationship is revealed when neuron-glia interactions are disrupted by neuronal ablation or mutation in the glial cells missing gene, which eliminates glia, when axons and glia cross the midline despite continued midline repellent signalling.

Animals↗
PubMed2005

Effect of temperature on the longitudinal variability of quantitative ultrasound variables.

It is unclear whether longitudinal change in phantom measurements bears any relation to the long-term in vivo instrument performance of quantitative ultrasound devices. Longitudinal quantitative ultrasound phantom data were obtained by measuring the manufacturer-provided phantom at ambient temperature and two different sets of Leeds phantoms at either ambient temperature or following a phantom temperature-control protocol. Measurements were performed using the Achilles Plus bone densitometer. Changes in longitudinal phantom data were compared to in vivo quantitative ultrasound data obtained from seven healthy, young volunteers. A cosinor model with linear trend and Hotelling's T2-test were used to quantify seasonal rhythms and long-term drift in quantitative ultrasound variables. Temperature effects and marked seasonal rhythms on quantitative ultrasound phantom measurements were evident but were far less apparent in vivo. Longitudinal precision of quantitative ultrasound variables was poorer for the manufacturer-provided phantom than for phantoms that were subjected to a temperature-control protocol or for healthy volunteers. This study has shown that longitudinal precision and longitudinal change differs between in vivo and phantom data. Longitudinal quantitative ultrasound measurements for monitoring change in skeletal status cannot, as yet, be properly controlled.

Adult↗
PubMed2002

Longitudinal processes in Salto Grande Reservoir (Americana, SP, Brazil) and its influence in the formation of compartment system.

Studies on the longitudinal processes in reservoirs, involving physical, chemical and biological processes have been thoroughly appraised, suggesting the existence of a longitudinal organization controlled by the entrance and circulation of water which inserts modifications in the structuring of the system. To evaluate this effect, the Salto Grande reservoir (Americana, SP) was analyzed in 11 sampling stations in its longitudinal axis, in the rainy and dry seasons of 1997 considering the physical chemical and biological variables. Analyzing the results in agreement with the declining concentration degree of the river-barrage direction, a more significant correlation was verified in the dry period for total phosphorus (r2 = 0.86), dissolved total phosphate (r2 = 0.83), nitrite (r2 = 0.93), inorganic phosphate (r2 = 0.89), ammonium (r2 = 0.84) and suspended material (r2 = 0.85). In the rainy period, only nitrite (r2 = 0.90) and conductivity (r2 = 0.89) presented correlation with the distance of the dam, which demonstrates the effects of precipitation and the operational mechanism of the dam, as well as the distinction among the physical (sedimentation), chemical (oxidation) and biological (decomposition) processes in spatial heterogeneity of the system. These factors were decisive in the organization of these communities, with higher occurrence of rotifers and copepods in relation to cladocerans, the first ones being more abundant in the entrance of the Atibaia river, decreasing towards the dam direction, while copepods presented an inverse pattern. A distribution pattern similar to Copepoda was also verified for the Cladocera, evidencing a tendency to increase the density of organisms in the stations distant to the entrance of the Atibaia river, not being registered, however, a distribution gradient in the longitudinal axis, as observed for rotifers and copepods. In relation to the trophic degree a longitudinal gradient was also verified from eutrophic to oligotrophic depending on the location of the sampling station in relation to the longitudinal axis and period of analysis. The differences obtained, relating to the distribution of the environmental variables, demonstrate a characteristic pattern for reservoirs, with a longitudinal gradient in the sense river-barrage that inserts changes in the physical and chemical composition of the water, contributing to the differentiated establishing of biological communities.

Animals↗
PubMed1979

Effects of stimulation of Auerbach's plexus on both longitudinal and circular muscles.

The effects of repetitive electrical stimulation of a node of Auerbach's plexus on both longitudinal and circular muscles were investigated by simultaneous recording of both muscle contractions. L-formed muscle strips, longitudinal and circular muscle strips, were made from a segment of rabbit small intestine. One strip was cut along, another strip was cut at 90 degrees to the oral-anal axis. The longitudinal muscle strip was peeled and Auerbach's plexus was exposed. Under a stereodissecting microscope the stimulating electrode, with tip diameter of 5--10 micron, was placed on a node of Auerbach's plexus situated at the junction of both muscle strips. Repetitive electrical stimulation of a node produced a mainly excitatory effect on spontaneous contractions of an orally-directed longitudinal muscle strip, excitatory and inhibitory effects on an anally-directed longitudinal muscle strip and a mostly excitatory effect on a circular muscle strip which always appeared with a delay after that on the longitudinal muscle. In a few instances the inhibitory effect of nodal stimulation was observed on the circular muscle. The evoked excitatory effect of longitudinal muscle was mainly due to a cholinergic mechanism, while that of circular muscle was partially due to cholinergic and partially noncholinergic activity. The evoked inhibition was nonadrenergic.

Acetylcholine↗
PubMed2004

Tissue Doppler assessment of diastolic and systolic alterations of radial and longitudinal left ventricular motions in Golden Retrievers during the preclinical phase of cardiomyopathy associated with muscular dystrophy.

OBJECTIVE: To quantify radial and longitudinal left ventricular free wall (LVFW) velocities in dogs during the preclinical phase of Golden Retriever muscular dystrophy (GRMD)-associated cardiomyopathy by use of tissue Doppler imaging (TDI). ANIMALS: 9 dogs with GRMD and 6 healthy control dogs. PROCEDURE: All dogs (< 3 years old) were examined via conventional echocardiography and 2-dimensional color TDI. Myocardial velocities in the LVFW were recorded from right parasternal ventricular short-axis (radial motion) and left apical 4-chamber (longitudinal motion) views. Cardiac assessments via TDI included maximal systolic and early and late diastolic LVFW velocities in the endocardial and epicardial layers (for radial motion) and in the basal and apical segments (for longitudinal motion) (for longitudinal motion), RESULTS: -No notable ventricular dilatation or alteration of inotropism was detected in dogs with GRMD via conventional echocardiography. Compared with healthy dogs, endocardial velocities were significantly decreased in dogs with GRMD, resulting in marked decreases in radial myocardial velocity gradients during systole and early and late diastole. Similarly, basal and apical velocities were significantly decreased in systole and the former also in early diastole, resulting in significant decreases in the 2 corresponding longitudinal myocardial velocity gradients. The radial epicardial and longitudinal late diastolic velocities were comparable in the 2 groups. CONCLUSION AND CLINICAL RELEVANCE: Results indicated that GRMD-associated cardiomyopathy in dogs is associated with early marked dysfunction of both radial and longitudinal LVFW motions. These combined regional myocardial abnormalities might be useful criteria for detection of dilated cardiomyopathy at the preclinical stage of the disease in dogs.

Analysis of Variance↗
PubMed1976

Longitudinal tension of anterior tibial artery segments during constrictor responses.

Longitudinal tensions were recorded from in situ isolated segments of dog anterior tibial arteries during vasoconstrictor responses. Two factors appeared to be responsible for longitudinal tensions occurring during vasoconstrictor responses. One was due to changes in intraluminal pressure and appeared to be the dominant factor. Increases in intraluminal pressures produced decreases in longitudinal tensions, indicating that the vessel segments were elongated. Thus, increases in intraluminal pressure passively stretched the blood vessel walls so that increases in both the circumferential and longitudinal axes of the vessel segment occurred. These findings agree with similar findings reported earlier (4, 7, 8). The other factor was apparently due to changes in longitudinal tension produced by vascular smooth muscle contraction. In some cases longitudinal tension changes were positive, in others they were negative. Increases in longitudinal tension were probably the result of contractions of helical smooth muscle elements. Decreases in tension may have been due to displacement of tissue parallel to the long axis of the vessel as smooth muscle elements contracted.

Animals↗
PubMed2001

Aging effects on contractility of longitudinal and circular detrusor and trigone of rat bladder.

PURPOSE: Aging is associated with bladder dysfunction, including difficult voiding and urinary leakage. Voiding involves reduction in the bladder lumen in all dimensions brought about by contraction of the meshwork of longitudinal, circular and oblique layers of detrusor smooth muscles. Most in vitro physiological studies of the effects of aging on bladder function used the longitudinal detrusor. To understand the region specific effects of aging on bladder function the contractile responses of longitudinal and circular detrusor, and trigone segments of the bladder from young and old rats were monitored. MATERIALS AND METHODS: These studies were performed using male Fisher 344 rats 6 months (young) and 27 months (old) old obtained through the National Institute on Aging. Each rat was anesthetized and the bladder was isolated. From each bladder a strip of longitudinal detrusor, circular detrusor and trigone was isolated and mounted in an in vitro multi-muscle chamber containing normal physiological solution at 37C. Isometric contractions of the 3 bladder strips were monitored after electrical field stimulation, 120 mM. potassium and 1 to 1,000 microM. bethanechol using a digital oscilloscope. RESULTS: In longitudinal detrusor from old rats there was no significant difference in the contractions evoked by electrical stimulation or high potassium but there was a significant reduction in contractions evoked by bethanechol compared with the responses of longitudinal detrusor from young rats. In circular detrusor from old rats there was a significant increase in contractions evoked by electrical stimulation and a slight increase in contractions produced by high potassium but no significant change in contractions evoked by bethanechol compared with the responses of circular detrusor from young rats. In trigone from old rats there was a significant decrease in contractions evoked by electrical stimulation, high potassium and bethanechol compared with young trigone. CONCLUSIONS: The reduction in contractions evoked by bethanechol suggests an age related reduction in muscarinic receptors in the longitudinal detrusor of aged rats. An increase in contractions evoked by electrical stimulation without a change in contractions evoked by bethanechol suggests a decrease in compliance caused by an increase in collagen in the circular detrusor of aged rats. A general decline in all contractile responses, including those evoked by high potassium, suggests reduced membrane depolarization in the trigone of aged rats. The effect of aging is specific to different regions and functional components of the bladder, probably due to changes in muscarinic receptors, collagen and depolarization.

Aging↗
PubMedDate not supplied

Longitudinal residency training in family medicine: not ready for prime time.

Many family medicine educators have called for changing the family practice residency curriculum from a series of block rotations to a longitudinal curriculum. A longitudinal curriculum is one in which residents are based in the family practice center every day or nearly every day of all 3 years of their residency training. Residents learn most of the clinical content offamily medicine through experiences with patients from their continuity clinics, under supervision of family medicine faculty, rather than through specialty-specific block rotations supervised by specialists. An important purported benefit of longitudinal training is improved continuity of care between residents and their patients. Unfortunately, definitions of longitudinal training vary widely, and at least one study shows that supposedly longitudinal curricula do not result in better continuity of care. Further, there is some evidence that acquisition of knowledge by residents may be better with intensive block rotations than with longitudinal training. Thus, the supposed benefits of longitudinal residency training remain unproven.

Adult↗