Autonomic innervation of rabbit urinary bladder following estrogen administration

The effects of estrogen administration on the autonomic innervation of the rabbit urinary bladder were studied. Immature female white rabbits were injected twice daily with estrogen (150 μg./Kg.) for four consecutive days. Control animals received injections of vehicle alone. The adrenergic innervation was identified using the glyoxalic acid method of catecholamine histofluorescence. The cholinergic innervation was visualized utilizing specific acetylcholinesterase staining. Additionally, the effect of estrogen administration on the response of smooth muscle strips of urinary bladder to specific autonomic agonists was determined. Estrogen administration induced a moderate increase in the adrenergic innervation of the rabbit bladder detrusor, whereas no change could be observed in the cholinergic innervation. It should be noted, however, that whereas the adrenergic innervation in the bladder of the control animal was sparse, the cholinergic innervation in the bladder body was quite dense. Estrogen induced a marked increase in the response to alpha -adrenergic (methoxamine) and muscarinic cholinergic (bethanechol) agonists. No alterations were noted in the response to beta-adrenergic agonists (isoproterenol). These findings indicate that the urinary bladder responds as a target organ of estrogen-induced alterations in autonomic innervation.     

Effect of distension on function and nervous ultrastructure in the canine urinary bladder

Canine bladders were distended for 4 h at 100 cm H2O to study the effects of distension on bladder function and structure. A micturition study was performed before overstretching, immediately after distension and 5 days after it. Bladder function was impaired immediately after distension, compliance and residual urine were increased and the maximum pressure during voiding decreased. The function returned to normal after 5 days. Overstretching caused diffuse or focal submucosal haemorrhages, only rarely fibrosis or necrosis of bladder wall. Electron microscopic changes of the bladder peripheral nerves were slight, the consistent finding being oedema in areas of outer mesoaxons and between cytoplasmic processes of Schwann cells. This change was sometimes accompanied by a rupture of the surrounding basement membrane. Axonal lysis was observed in one case. It is concluded that these anatomical changes, although found at the moment of functional recovery, may be linked to impaired conductivity of nerves in the bladder wall causing, at least partly, its impaired function. This may further decrease bladder instability and after urinary retention cause prolonged micturition problems. Functional recovery occurs, however, quite rapidly in healthy bladders.     

Effect of distension on adrenergic innervation of the rat urinary bladder

Summary The effect of distension on adrenergic innervation was investigated in the rat urinary bladder. Bladders were distended for 3 h by forced diuresis and ballon obstruction, and specimens were taken from the bladder dome, body and neck for the demonstration of glyoxylic acid-induced fluorescence of catecholamines. Depletion of catecholamines started after 10 h and was almost complete after 2 days. The fluorescence had recovered part way after 5–7 days and was practically normal after 21 days. Small, intensely fluorescent (SIF) cells in the ganglia continued to leak catecholamines throughout the 21-day study period. The primary clinical success of distension therapy for the treatment of unstable bladder may be at least partly due to a reversible disturbance in the function of the adrenergic nerves, which have an excitatory alpha-adrenergic dominance in such cases, but the persistent leakage from SIF cells raises the question of whether distension causes prolonged disturbances in bladder function.     

Cholinergic and adrenergic neuroreceptors in urinary tract of female dogs. Evaluation of function with pharmacodynamics.

Our preliminary pharmacodynamic studies on the lower urinary tract of adult female dogs indicate that cholinergic and adrenergic (alpha and beta) neuroreceptors in the urethra appear to coordinate the detrusor and urethral function during micturition. Urethral resistance measured as urethral pressure was easily altered with various pharmacologic agents. However, only bethanechol elicited detrusor response measured as intravesical pressure. The possible clinical usefulness of various drugs is outlined. Our results indicate the therapeutic value of ephedrine sulfate and propranolol in stress urinary incontinence; phenoxybenzamine in neurogenic vesical dysfunction and functional outlet obstruction; phenoxybenzamine plus bethanechol in atonic neurogenic bladder; and imipramine in enuresis.     

Effects of pregnancy on adrenergic function in the rabbit urinary bladder

Pregnancy induces morphological as well as functional changes in the urinary tract. Urinary frequency, incontinence, and an increase in residual urine are common clinical findings during gestation. Previous studies from this laboratory have shown a decreased cholinergic response and cholinergic receptor density in the urinary bladders of pregnant rabbits. In the present study, the adrenergic functions of the bladders of pregnant and virgin New Zealand White rabbits were compared using isolated muscle strips. Dose-response curves showed that the contractile responses to epinephrine (alpha and beta agonist) and methoxamine (alpha agonist) were significantly reduced in tissues from the base and the mid-segment, but not the body of the pregnant rabbit bladders. No significant difference was observed in the degree of isoproterenol (beta agonist) induced relaxations between the two groups. Thus, the results demonstrated a decreased alpha responsiveness in the midsegment and base of the pregnant bladders. Physiologically, a decrease in alpha tone at the bladder base would be advantageous for bladder emptying as the resultant relaxation at the bladder outlet theoretically would alleviate the effect of decreased bladder body contractility as well as any mechanical stress imposed on the urethra by the enlarging uterus.     

Sympathetic innervation and chemical sympathectomy of canine bladder

Chemical sympathectomy of the dog bladder produced by intra-aortic injection of 6-hydroxydopamine has been shown to increase the slope of the pressure/volume curve obtained by rapid fill cystometry. The volume threshold for eliciting a bladder contraction was decreased, whereas the pressure threshold did not change. Peripheral autonomic nervous elements in the bladder wall are described which are proposed as the morphologic basis for these and other such modulating influences.     

Autonomic nervous system and adrenergic receptors in chronic hypotensive haemodialysis patients

Background. The pathophysiology of chronic hypertension (CH) in uraemia is not elucidated. The possible role of autonomic nervous system dysfunction and adrenoceptor alterations in the pathophysiology of CH in uraemia was evaluated in this study. Methods. Seventeen hypotensive haemodialysis (HD) patients, 17 normotensive HD patients, and 17 control subjects were studied. We evaluated the integrity of the baroreflex arc (Valsalva manoeuvre), the parasympathetic efferent pathway ('deep-breathing test') and the sympathetic efferent pathway ('hand-grip test'). We also evaluated platelet &agr;2-adrenoceptor and lymphocyte {beta}2-adrenoceptor densities (radioligand binding assay), and {beta}2-adrenoceptor response (intracellular cAMP generation after isoproterenol stimulation in lymphocytes). Results. Responses to the Valsalva manoeuvre and the deep-breathing test were altered in all HD patients (P <0.05). Valsalva ratio was lower in hypotensive patients than in normotensive patients (P <0.01), whereas the pressor response to the hand-grip test was reduced only in hypotensive HD patients (P <0.01). In haemodialysed patients, basal mean blood pressure (MBP) correlated with MBP increases during the hand-grip exercise (r = 0.59, P <0.01). Plasma catecholamine levels were elevated in both groups of patients (P <0.025). Plasma adrenaline levels were higher in hypotensive HD patients than in normotensive patients (P <0.05). &agr;2- and {beta}2-adrenoceptor densities and {beta}2-adrenoceptor response were reduced in hypotensive patients (P <0.05 vs normotensive patients). MBP correlated with &agr;2-adrenoceptor (r = 0.46, P <0.01) and {beta}2-adrenoceptor (r = 0.43, P <0.025) densities in HD patients. Conclusions. Normotensive haemodialysed patients have increased plasma catecholamine levels with preserved &agr;2- and {beta}2-adrenoceptor numbers, as well as {beta}2-adrenoceptor responses. In hypotensive patients, plasma adrenaline levels were even higher; the increased plasma catecholamine levels induced an &agr;2- and {beta}2-adrenoceptor downregulation. This downregulation may play a role in the reduced cardiovascular responses to adrenergic stimuli reported in hypotensive HD patients.     

Synchronized electrical stimulation of the sympathetic and parasympathetic innervation of the bladder: facilitation of the initiation of micturition in the dog

To improve the quality of bladder contractions induced by parasympathetic stimulation and to facilitate the initiation of voiding, we investigated the effect of sympathetic stimulation on the parasympathetic innervation of the bladder in 12 dogs. For the sympathetic system, the lumbar sympathetic trunks were electrically stimulated; for the parasympathetic system, either the pelvic nerve or the ventral root of S2 was stimulated. With voltages at or just above the threshold for achieving a measurable effect on bladder pressure, stimulation of the sympathetic system or the pelvic nerve alone did not lead to voiding, and sacral root stimulation alone elicited voiding in only 7.4 per cent of stimulations. However, when the same stimulus parameters were used for synchronous stimulation, the voiding process was facilitated when sympathetic stimulation was begun five to 10 seconds before parasympathetic stimulation. When the pelvic nerve was used, voiding resulted in 77.7 per cent of stimulations and the bladder was emptied by a mean of 68.7 per cent; with S2 ventral root stimulation, voiding resulted in 83.3 per cent of stimulations and the bladder was emptied by 59.7 per cent. The facilitory effect of sympathetic stimulation was not abolished when the sympathetic trunks were cut centrally to the point of stimulation, but was absent when the hypogastric nerves were transected. We feel that sympathetic stimulation modulates the parasympathetic innervation of the bladder.     

Innervation of trigonal area of canine urinary bladder.

Adrenergic and cholinergic histochemical staining techniques and in vitro muscle strip responses to adrenergic and cholinergic stimulation and blockade have failed to demonstrate any neuromorphologic or neuropharmacologic differences between the musculature of the canine trigone and that of the underlying detrusor. There is no evidence to suggest that a functional potential could be attributed to the trigone separate from that of the related bladder base.     

Effect of prolonged experimental distension on the function and ultrastructure of the canine urinary bladder.

Urinary bladder distension was induced for 10 hours in dogs and micturition tests were made before over-stretching, immediately afterwards and 5 days later. Compliance and residual urine had increased and maximum pressure during voiding had decreased immediately after retention, but returned to normal after 5 days. Biopses for light microscopic and electronmicroscopic investigation taken from the anterior wall of the bladder on the fifth day showed submucosal haemorrhages and some necrosis. The consistent finding on electron microscopy was Schwann cell oedema, which was seen within the cytoplasm and between the cytoplasmic processes of the Schwann cells. Axonal degeneration was also a common finding. These anatomical changes, although found at the moment of functional recovery, may be linked to impaired conductivity of the nerves in the bladder wall, at least partly, causing its impaired function. Recovery of function occurs quite rapidly in healthy bladders.     

Effect of bladder outflow obstruction on the innervation of the rabbit urinary bladder.

The effects of bladder outflow obstruction on the innervation of the bladder were studied using a rabbit animal model. Partial occlusion of the bladder neck was obtained by the placement of a silk ligature at that level; control animals underwent a sham procedure. After a 3-month period, the presence of outflow tract obstruction was confirmed using urodynamic studies. The animals were then killed and pharmacological assessments of the bladder innervation undertaken. Detrusor muscle strip studies provided evidence of damage to the cholinergic innervation of the detrusor. Also, muscle strips from obstructed animals showed reduced inhibitory responses to beta-adrenergic stimulation with isoprenaline. In addition to these muscle strip studies, the bladder content of the neuropeptide substance P was assayed, but no significant change was observed in response to obstruction. This finding suggests that substance P-containing sensory nerves may be spared from the denervating effect of bladder outflow obstruction.     

Comparison of muscarinic cholinergic and alpha adrenergic receptors in canine ileum, colon, intestinal urinary reservoirs and bladder

The muscarinic cholinergic (MCh) and alpha 2 adrenergic receptor densities in canine ileum, colon, ileal and colonic urinary reservoirs and bladder were determined using radioligand receptor binding methods in order to provide a rational basis for pharmacologic management of urinary incontinence following bladder replacement with intestinal segments. Muscarinic cholinergic and alpha 2 adrenergic receptor binding sites were studied in these tissues using saturation experiments with 3H-NMS and 3H-rauwolscine, respectively. The mean equilibrium dissociation constants for 3H-NMS binding (0.13 to 0.17 nM) in these tissues were similar (p greater than 0.05) indicating homogeneity of muscarinic cholinergic binding sites. The mean equilibrium dissociation constants for 3H-rauwolscine binding (1.27 to 1.98 nM) in these tissues were also similar (p greater than 0.05). A substantial density of MCh (1.06 to 1.22 fmol/mg. wet wt.) and alpha 2 adrenergic (0.47 to 1.11 fmol/mg. wet wt.) binding sites was identified in the intestinal tissues assayed. The density of ileal and colonic MCh and alpha 2 adrenergic binding sites was not altered following construction of urinary intestinal reservoirs. The presence of a substantial density of MCh and alpha 2 adrenergic binding sites in the intestinal tissues suggests that MCh and alpha 2 adrenergic analogs may be utilized for the management of urinary incontinence following bladder replacement with intestinal urinary reservoirs.     

Acinar structure and function in canine pancreatic autografts with duct drainage into the urinary bladder

Autotransplants of pancreas in 8 dogs, with exocrine drainage into the urinary bladder, were stimulated in vivo with cholecystokinin-pancreozymin (CCK-PZ). Transplant biopsies, when compared with 6 normal pancreases, showed normal acinar structure by light and electron microscopy 13-18 months after initial surgery; 2 transplants with sutures unintentionally transecting ducts were fibrosed and had duct obstruction. After in vivo stimulation, the normal-appearing transplants produced a 7-fold increase in urinary amylase, and quantitative electron microscopy showed a 50% reduction in mature zymogen granules; there were no intracellular organelle abnormalities prior or subsequent to stimulation. Fibrosed transplants produced lesser urinary amylase both prior to and after stimulation. In vitro stimulation of grafts with normal structure increased amylase secretion from 1.5-2.1-fold. In vitro dose-response showed a maximum at 10(-9)M cholecystokinin-octopeptide (CCK-OP) in transplant and control. The in vivo stimulation is more responsive and may be useful for clinical monitoring of graft survival. In vivo stimulation occurred after induced urinary tract infection; because no pancreatitis ensued, a regimen of trophic stimulation by CCK-PZ was not contraindicated. The bladder tolerated exocrine drainage with no significant change, and bladder infection did not adversely affect the transplant. The islets appeared normal in the transplants by light and qualitative electron microscopic observation; fasting blood glucose and insulin values were normal during the 12-18-month follow-up. Bladder drainage of segmental grafts of pancreas provides a preparation with intact acinar-islet relationships; the present observations suggest that this may permit longer islet survival in the absence of acinar destruction and subsequent fibrosis.     

Autonomic neuropathy in BB rats and alterations in bladder function

In vivo urinary bladder function was examined in BB rats after 4 and 6 mo of diabetes, and the data were correlated with morphometric changes in the pelvic and hypogastric nerves, which constitute the micturition reflex arc. After controlled bladder distension, diabetic animals revealed irregular bladder contractions at frequencies that were reduced to 33% of normal values and with significantly increased amplitudes. The abnormal micturition in diabetic animals was elicited at moderately elevated threshold volumes. These functional abnormalities of the diabetic bladder were associated with a progressive axonopathy of afferent myelinated sensory fibers and later-occurring axonal atrophy of unmyelinated efferent preganglionic fibers. These data suggest that diabetic urinary bladder dysfunction is initiated by a visceral sensory neuropathy involving the afferent limb of the micturition reflex arc.