Alpha- and beta-adrenoceptors in the female dog urethra

The existence and subtypes of alpha- and beta-adrenoceptors in the female dog urethra were studied in vivo and in vitro by means of agonist and antagonist drugs. Noradrenaline, phenylephrine and B-HT 920, stimulants of alpha, alpha-1 and alpha-2 receptors respectively, caused an increase in the urethra tonicity. Thus indicating that the contractile activity is mediated by alpha-1 and alpha-2 adrenoceptors subtypes. On the other hand, the inhibitory urethral activity is under control of beta-adrenoceptors of beta-2 subtype, since the isoprenaline relaxing action is inhibited when beta-2 receptors are blocked, whilst this effect was not observed when beta-1 receptors were blocked. This fact was proved when beta-2 receptors were stimulated with salbutamol.     

Innervation of the proximal urethra of ovariectomized and estrogen-treated female rats

The proximal urethra plays a central role in maintaining urinary continence, and sympathetic excitatory innervation to urethral smooth muscle is a major factor in promoting tonic contraction of this organ. Elevated estrogen levels are often associated with incontinence in humans. Because elevated estrogen levels result in degeneration of sympathetic nerves from the closely related uterine smooth muscle, we examined the effects of chronic estrogen administration on proximal urethral innervation. Ovariectomized virgin female rats received either vehicle or 17 beta-estradiol for 1 week, and smooth muscle size and parasympathetic, sensory and sympathetic nerve densities were assessed quantitatively throughout the first 3 mm of the proximal urethral smooth muscle. In vehicle-infused ovariectomized rats, parasympathetic nerves immunoreactive for vesicular acetylcholine transporter were most abundant, while calcitonin gene-related peptide-immunoreactive sensory nerves and tyrosine hydroxylase-immunoreactive sympathetic nerves were less numerous. The densities of parasympathetic and sensory nerves remained constant along the proximal urethra, while sympathetic nerves showed a significant increase along a proximal-distal gradient. Administration of 17beta-estradiol for 7 days via subcutaneous osmotic pump did not change smooth muscle area in sections, and neither densities nor total innervation of any nerve population was altered. These findings reveal a rich cholinergic innervation of the proximal urethra, and a pronounced gradient in sympathetic innervation. Unlike the embryologically similar uterine smooth muscle, estrogen does not influence muscle size or composition of innervation, indicating that estrogen's actions on innervation are highly target-specific. Thus, estrogen's effects on urinary continence apparently occur independently of any significant remodeling of smooth muscle or resident innervation.     

Clear-cell carcinoma in the trachea of a rat.

Necropsy examination of a control Sprague-Dawley male rat from a carcinogenicity study disclosed the presence of a neoplastic mass in the trachea. Microscopic examination disclosed that the tumor consisted of closely packed cells arranged in lobules and cords separated by thin connective tissue stroma. The cells had distinct cell borders and abundant pale cytoplasm. Electron microscopic examination further disclosed that the cytoplasm contained numerous argyrophilic neurosecretory granules measuring 298 nm in diameter. These granules were positive for Grimelius silver stain. The histopathologic and electron microscopic features of this tumor are consistent with a diagnosis of clear-cell carcinoma.     

Spinning top urethra and lower urinary tract dysfunction in a young female

Spinning top urethra (STU) denotes a particular urethral configuration that is a dilated posterior urethra mainly seen in young girls or women. STU deformity arises secondary to detrusor instability, leading to a rise the intravesical pressure against a closed sphincter. We describe a case of spinning top urethra in a 30-year-old woman who presented with lower urinary tract symptoms and left flank pain.     

Stenosing colonic adenocarcinoma in a female rhesus monkey

Abstract: Laparoscopic surgery was performed on a 16 year-old female rhesus monkey presenting with chronic lethargy and inappetence. The procedure revealed a “napkin-ring” stricture located in the ascending large colon. Histologic evaluation of the colonic lesion exhibited large numbers of irregular acini lined by a single layer of well-differentiated neoplastic epithelial cells. Based on the gross and histopathologic findings a diagnosis of adenocarcinoma of the proximal colon was made.     

Mammary adenocarcinoma in a young female hypercholesterolemic rat.

Pathological examination of a 12-week-old female rat with hypercholesterolemia revealed mammary adenocarcinoma. Grossly, one grayish-white nodule was found in the hypoderm near the right posterior mammary gland. Histologically, the nodule was composed of variable-sized epithelial cells which lined the tubules and ducts in one to several layers, accompanied by proliferation of connective tissue in the stroma. Mitotic figures, necrosis and hemorrhage appeared frequently throughout the lesion. The tumor cells had invaded the surrounding muscular tissue.     

A histological study of the Shionogi adenocarcinoma 115 grown in male and female mice

We have previously demonstrated that growth rate and morphology differ between androgen-responsive Shionogi mouse mammary tumours maintained in male and female mice. Furthermore, we can modulate the growth rate of these tumours in male mice by exposing the mice to psychosocial stressors. In the present study, we were interested in determining if tumours in male mice with a comparable growth rate to that in females, also had a morphology similar to that in females. SC115 tumours were examined using histochemical and immunohistochemical techniques. Tumours in male mice were easily distinguishable from tumours in female mice regardless of growth rate. Tumours maintained in female mice contained osteoid-like regions which stained positive for sialic acid and sulphate moieties. No such regions were observed in any of the tumours from male mice. In addition, although all tumours contained MSA (muscle specific actin)-positive and S100 protein-positive cells, these regions were more extensive in the tumours of female mice. This study suggests that tumour growth rate and morphology are independently regulated by the host environment.     

Ion channels of the mammalian urethra

The mammalian urethra is a muscular tube responsible for ensuring that urine remains in the urinary bladder until urination. In order to prevent involuntary urine leakage, the urethral musculature must be capable of constricting the urethral lumen to an extent that exceeds bladder intravesicular pressure during the urine-filling phase. The main challenge in anti-incontinence treatments involves selectively-controlling the excitability of the smooth muscles in the lower urinary tract. Almost all strategies to battle urinary incontinence involve targeting the bladder and as a result, this tissue has been the focus for the majority of research and development efforts. There is now increasing recognition of the value of targeting the urethral musculature in the treatment and management of urinary incontinence. Newly-identified and characterized ion channels and pathways in the smooth muscle of the urethra provides a range of potential therapeutic targets for the treatment of urinary incontinence. This review provides a summary of the current state of knowledge of the ion channels discovered in urethral smooth muscle cells that regulate their excitability.     

A mathematical model of the urethra

Models having the form of surfaces of revolution may be used to represent the urethra under pre-voiding pressure. From such models are derived formulas for calculating muscle tension from the shape of a urethragram.     

A mathematical model of the urethra

Models having the form of surfaces of revolution may be used to represent the urethra under pre-voiding pressure. From such models are derived formulas for calculating muscle tension from the shape of a urethragram.     

Ion channels of the mammalian urethra

The mammalian urethra is a muscular tube responsible for ensuring that urine remains in the urinary bladder until urination. In order to prevent involuntary urine leakage, the urethral musculature must be capable of constricting the urethral lumen to an extent that exceeds bladder intravesicular pressure during the urine-filling phase. The main challenge in anti-incontinence treatments involves selectively-controlling the excitability of the smooth muscles in the lower urinary tract. Almost all strategies to battle urinary incontinence involve targeting the bladder and as a result, this tissue has been the focus for the majority of research and development efforts. There is now increasing recognition of the value of targeting the urethral musculature in the treatment and management of urinary incontinence. Newly-identified and characterized ion channels and pathways in the smooth muscle of the urethra provides a range of potential therapeutic targets for the treatment of urinary incontinence. This review provides a summary of the current state of knowledge of the ion channels discovered in urethral smooth muscle cells that regulate their excitability.