On the etiology of the electric activity of the external anal and urethral sphincters.

UNLABELLED: In a previous study, the external anal sphincter (EAS) in dogs, known to consist of skeletal muscle fibers, was proved to contain bundles of smooth muscle fibers in between as well. OBJECTIVE: Cause of electric activity in the external anal and urethral sphincters is not known; the current study investigated this point. MATERIAL AND METHODS: Slices from external anal and urethral sphincters of 21 cadavers (12 male, 9 female). Eighth were fully and mat wide neonates, 13 were adults, were stained with hematoxylin and eosin, Masson's trichrome and succinic dehydrogenase, and examined microscopically. Eighteen healthy volunteers, electromyography activity of their external anal and urethral sphincters was recorded at rest, on coughing, after pudendal nerve block and after drotaverine administration, (a smooth muscle relaxant). Anal and urethral pressures were also measured. RESULTS: Microscopic studies have shown that both external anal and urethral sphincters were formed of bundles of smooth muscle fibers present in between the skeletal muscle fibers. Bilateral pudendal nerve block did not abolish the external anal or the urethral sphincters electromyography activity at rest, or on coughing, and did not cause significant anal or urethral pressure changes (p > .05). Drotaverine administration lead to disappearance of the electromyography activity and significant decline of the anal and urethral pressures (p < .05). The results were reproducible when the tests were repeated in the same subject. CONCLUSION: Histologic examination revealed the presence of smooth muscle fibers, between the skeletal fibers of the external anal and urethral sphincters. Evidence suggests that the smooth muscle fibers are the source of the electric activity of the sphincters and might explain some physiologic phenomena such as the external anal contraction on rectal distension or on coughing.

Tunica albuginea reefing: a novel technique for the treatment of erectile dysfunction.

BACKGROUND: "Tunica albuginea (TA) reefing" is a modification of Shafik's "TA overlapping" operation. Both techniques are based on the fact that in venogenic erectile dysfunction patients, the TA exhibits degenerative and atrophic collagen and elastic fibers causing its subluxation and flabbiness. This had led to loss of the veno-occlusive mechanism of the TA and venous leakage during erection. AIM: Reefing of the redundant tissue by bilateral excision of an ellipse of the TA provides a more effective correction of the TA and achieves a good support of the corpora cavernosa during tumescence. MATERIAL AND METHODS: The study included 24 patients with a mean age of 33.5 ± 1.7 SD years. Intracorporal pressure was measured preoperatively and postoperatively. After penile degloving, an ellipse was excised from both lateral aspects of the penile shaft, extending from the glans penis to its root, and the two edges of each wound were reefed by continuous Dexon suture. RESULTS: The TA ellipses were taken as biopsies and revealed degenerative changes when stained with hematoxylin and eosin and Masson's trichrome stain. Postoperatively, there was an intracorporal pressure increase (p < .01) in 20 out of 24 patients of the study and a decrease in 4 out of 24. Six months after operation, the patients showed significantly (p < .01) improved scores for the domain of erectile function over the preoperative scores. CONCLUSION: The reefing operation corrects the TA flabbiness to a greater extent, lends more support to corporal tissue, and improves the veno-occlusive mechanism.

Double-loop puborectoplasty: novel technique for the treatment of fecal incontinence.

The treatment of neurogenic and traumatic fecal incontinence (FI) as may result from severe anal sphincteric destruction is problematic. A novel technique for the treatment of these cases is presented. The study comprised 44 patients, which included 28 with neurogenic and 16 with traumatic FI. Patients were divided into two equal groups. Two fascia lata slings (FLS) were applied in Group 1, while one sling was used in Group 2. Investigations comprised manometric and electromyographic studies. The procedure consisted of performing a curvilinear incision behind the anal orifice, and the supralevator region was entered. The middle of an FLS was sutured to the back of the upper part of anal canal. Each of the two limbs of the sling was passed forward through an incision on the pubic ramus and was sutured to the periosteum of the pubic ramus. This was preformed in Groups 1 and 2. A second FLS was added in Group 1. Its center was sutured to the front of the mid anal canal and its two limbs to the coccyx. Satisfactory results (continence scores 1 and 2) were obtained in 63.6% of Group 1 and 36.4% of Group 2. Significant postoperative anal pressure increase occurred in scores 1 to 3 in Group 1 and in scores 1 to 2 in Group 2. Anal pressure increase was more prominent in Group 1 than in Group 2. The continent effect of the operation appears to be due to the increase of anal pressure, anal canal elongation, and recto-anal angulation. The operation is indicated in FI of the idiopathic or traumatic type with excessive sphincteric loss. It is simple and easy and performed under no cover of colostomy.

Effect of severe stress on the gastric motor activity: canine study of mechanism of action.

BACKGROUND: Increased gastric motility was observed during restraint stress in animals; however, mechanism of action could not be traced in literature. We investigated the hypothesis that high levels of stressful cutaneous stimuli induce increase of gastric motor activity through a reflex action. METHODS: Gastric tone (GT) was assessed in 14 dogs by barostat system consisting of balloon-ended tube connected to strain gauge and air-injection system. Tube was introduced into stomach and its balloon inflated with 150 mL of air. Thermal cutaneous stimulation (TCS) was performed by thermal plate applied to skin. Temperature was raised in increments of 5 degrees C up to 107 degrees C and GT was simultaneously assessed by recording balloon volume variations expressed as percentage change from baseline volume. Test was repeated after separate anesthetization of skin and stomach. RESULTS: TCS up to mean temperature of 48.7 +/- 1.1 degrees C effected significant decrease of GT, but significant increase beyond this temperature. Twenty minutes after individual anesthetization of skin and stomach, TCS produced no significant change in GT. CONCLUSION: TCS up to certain degree effected GT decrease, whereas TCS beyond this degree augmented the GT. These effects seem to be mediated through reflex action as evidenced by their absence on individual anesthetization of the suggested 2 arms of the reflex arc: skin and stomach; we call this reflex "cutaneo-gastric reflex." The reflex may have the potential to serve as an investigative tool in diagnosis of gastric motor disorders provided further studies are performed to reproduce current results.

An electrophysiologic study of female ejaculation.

Opinions vary over whether female ejaculation exists or not. We investigated the hypothesis that female orgasm is not associated with ejaculation. Thirty-eight healthy women were studied. The study comprised of glans clitoris electrovibration with simultaneous recording of vaginal and uterine pressures as well as electromyography of corpus cavernous and ischio- and bulbo-cavernosus muscles. Glans clitoris electrovibration was continued until and throughout orgasm. Upon glans clitoris electrovibration, vaginal and uterine pressures as well as corpus cavernous electromyography diminished until a full erection occurred when the silent cavernosus muscles were activated. At orgasm, the electromyography of ischio-and bulbo-cavernosus muscles increased intermittently. The female orgasm was not associated with the appearance of fluid coming out of the vagina or urethra.

Percutaneous perineal electrostimulation induces erection: clinical significance in patients with spinal cord injury and erectile dysfunction.

OBJECTIVES: Approximately one third to one half of the penis is embedded in the pelvis and can be felt through the scrotum and in the perineum. The main arteries and nerves enter the penis through this perineal part of the penis, which seems to represent a highly sensitive area. We investigated the hypothesis that percutaneous perineal stimulation evokes erection in patients with neurogenic erectile dysfunction. METHODS: Percutaneous electrostimulation of the perineum (PESP) with synchronous intracorporeal pressure (ICP) recording was performed in 28 healthy volunteers (age 36.3 +/-7.4 y) and 18 patients (age 36.6 +/- 6.8 y) with complete neurogenic erectile dysfunction (NED). Current was delivered in a sine wave summation fashion. Average maximal voltages and number of stimulations delivered per session were 15 to 18 volts and 15 to 25 stimulations, respectively. RESULTS: PESP of healthy volunteers effected an ICP increase (P < 0.0001), which returned to the basal value upon stimulation cessation. The latent period recorded was 2.5 +/- 0.2 seconds. Results were reproducible on repeated PESP in the same subject but with an increase of the latent period. Patients with NED recorded an ICP increase that was lower (P < 0.05) and a latent period that was longer (P < 0.0001) than those of healthy volunteers. CONCLUSION: PESP effected ICP increase in the healthy volunteers and patients with NED. The ICP was significantly higher and latent period shorter in the healthy volunteers than in the NED patients. PESP may be of value in the treatment of patients with NED, provided that further studies are performed to reproduce these results.

Effect of thermal cutaneous stimulation on the gastric motor activity: study of the mechanism of action.

AIM: To investigate the mechanism of action of thermal cutaneous stimulation on the gastric motor inhibition. METHODS: The gastric tone of 33 healthy volunteers (20 men, mean age 36.7 +/- 8.4 years) was assessed by a barostat system consisting of a balloon-ended tube connected to a strain gauge and air-injection system. The tube was introduced into the stomach and the balloon was inflated with 300 mL of air. The skin temperature was elevated in increments of 3 degree up to 49 degree and the gastric tone was simultaneously assessed by recording the balloon volume variations expressed as the percentage change from the baseline volume. The test was repeated after separate anesthetization of the skin and stomach with lidocaine and after using normal saline instead of lidocaine. RESULTS: Thermal cutaneous stimulation resulted in a significant decrease of gastric tone 61.2% +/- 10.3% of the mean baseline volume. Mean latency was 25.6 +/- 1.2 ms. After 20 min of individual anesthetization of the skin and stomach, thermal cutaneous stimulation produced no significant change in gastric tone. CONCLUSION: Decrease in the gastric tone in response to thermal cutaneous stimulation suggests a reflex relationship which was absent on individual anesthetization of the 2 possible arms of the reflex arc: the skin and the stomach. We call this relationship the "cutaneo-gastric inhibitory reflex". This reflex may have the potential to serve as an investigative tool in the diagnosis of gastric motor disorders, provided further studies are performed in this respect.

Study of the response of the penile corporal tissue and cavernosus muscles to micturition.

BACKGROUND: The reaction of the corpora cavernosa (CC), the corpus spongiosum (CS), the bulbocavernosus (BCM) and ischiocavernosus (ICM) muscles to passage of urine through the urethra during micturition is not known. We investigated the hypothesis that the passage of urine through the urethra stimulates the corporal tissue and cavernosus muscles. METHODS: In 30 healthy men (mean age 42.8 +/- 11.7 years), the electromyographic activity (EMG) of the CC, CS, BCM, and ICM were recorded before and during micturition, and on interruption of and straining during micturition. These tests were repeated after individual anesthetization of urethra, corporal tissue, and cavernosus muscles. RESULTS: During micturition, the slow wave variables (frequency, amplitude, conduction velocity) of the CC and CS decreased while the motor unit action potentials of the BCM and ICM increased; these EMG changes were mild and returned to the basal values on interruption or termination of micturition. Micturition after individual anesthetization of urethra, corporal tissue and cavernosal muscles did not effect significant EMG changes in these structures, while saline administration produced changes similar to those occurring before saline administration. CONCLUSION: The decrease of sinusoidal and increase of cavernosus muscles' EMG activity during micturition apparently denotes sinusoidal relaxation and cavernosus muscles contraction. Sinusoidal muscle relaxation and cavernosus muscles contraction upon micturition are suggested to be mediated through a 'urethro-corporocavernosal reflex'. These sinusoidal and cavernosus muscle changes appear to produce a mild degree of penile tumescence and stretch which might assist in urinary flow during micturition.

Inguinal canal dilatation: a novel technique for the repair of failed testicular descent despite hormonal treatment.

Treatment of the undescended testicle (UT) after it failed to descend on hormonal therapy is surgical. Spermatic cord elongation may impair testicular function, particularly in cases in which cord integuments or veins have to be divided to provide an extra cord length. A factor that might impede testicular descent is presence of a narrowed or obliterated inguinal canal. We investigated the hypothesis that dilatation of a narrowed or obliterated inguinal canal might assist spontaneous testicular descent. Twenty-six boys (age 3.6 +/- 0.8 years) with unilateral UT and failed hormonal treatment, whose UT was located at deep inguinal ring, were included in the study. Through an inguinal incision, the inguinal canal was dilated, spermatic cord adhesions divided, hernial sac, if present, excised, and skin closed. Testicular descent into the scrotum occurred in 22 patients within 4.2 +/- 1.3 months. The remaining four patients were reoperated on by Fowler-Stephens orchiopexy after 14 months. A technique is presented for the treatment of the UT after failure to respond to hormonal treatment. It consisted of clearing the testicular pathway of any adhesions and dilating the narrowed inguinal canal. The technique is simple, easy, and does not interfere with the testicle or spermatic cord.

Effect of micturition on clitoris and cavernosus muscles: an electromyographic study.

We investigated the hypothesis that passage of urine through urethra stimulates corporal tissue and cavernosus muscles. Electromyographic (EMG) activity of corpora cavernosa (CC), bulbocavernosus muscle (BCM), and ischiocavernosus muscle (ICM) was recorded in 27 healthy women before and during micturition. These tests were repeated after individual anesthetization of urethra, corporal tissue, and cavernosus muscles. During micturition, slow wave variables of CC decreased and motor unit action potentials of the BCM and ICM increased. These EMG changes returned to basal values on micturition interruption or termination. Micturition after individual anesthetization of the urethra, corporal tissue, and cavernosus muscles did not effect significant changes in these structures. Decreased EMG activity of CC and increased activity of cavernosus muscles during micturition apparently denotes corporal tissue relaxation and cavernosus muscles' contraction. The latter two actions occurring on micturition are suggested to be mediated through a reflex called "urethro-corporocavernosal reflex" and effect a mild degree of clitoral tumescence.

The electromyographic activity of the external and internal urethral sphincters and urinary bladder on vaginal distension and its role in preventing vaginal soiling with urine during sexual intercourse.

BACKGROUND/AIM: We investigated the hypothesis that external (EUS) and internal (IUS) urethral sphincters and urinary bladder (UB) respond to penile thrusting (PT) of vagina in a way that prevents urinary leakage during coitus. METHODS: Vaginal condom was inflated with air in increments of 50-300 ml and EMG of EUS and IUS and vaginal pressure were recorded; test was repeated after anesthetization of vagina, UB, EUS, and IUS. RESULTS: Vaginal distension effected reduction of vesical pressure but increase of IUS EMG until the 150 ml distension was reached, beyond which more vaginal distension caused no further effect; EUS EMG showed no response. Vaginal distension while vagina, UB, EUS, and IUS had been separately anesthetized, produced no change. CONCLUSION: Vaginal balloon distension appears to effect vesical relaxation and increased IUS tone. This seems to provide a mechanism to avoid urine leakage during coitus and to occur through a reflex we term 'vagino-urethrovesical reflex'.

Electromyographic lag time and opening time: two novel noninvasive methods to investigate patients with anal outlet obstruction and their response to treatment.

Methods in use can diagnose anal outlet obstruction but not degree of obstruction. We introduced two novel noninvasive methods of diagnosing and evaluating the degree of anal outlet obstruction: pelvic floor electromyographic lag time and opening time. Pelvic floor electromyographic lag time measured time interval between start of pelvic floor muscle relaxation and start of anal outlet flow. Opening time calculated time lapse between start of rectal contraction and start of anal outlet flow. We investigated the hypothesis that pelvic floor electromyographic lag time and opening time can be used as investigative tools in diagnosing and evaluating degree of anal outlet obstruction. Thirty-one patients with anal outlet obstruction and 26 healthy volunteers were studied. Electromyography of external anal sphincter and anal and rectal pressures were recorded on rectal balloon distension until balloon was expelled. Pelvic floor electromyographic lag time and opening time were measured. Mean opening time and pelvic floor electromyographic lag time of the anal outlet obstruction patients showed significant increase compared to those of healthy volunteers. Pelvic floor electromyographic lag time was longer than opening time in both patients and controls, but the difference was not significant. Biofeedback effected improvement in 24 of the 31 patients. Thus, two novel investigative tools -- opening time and pelvic floor electromyographic lag time -- in diagnosis of anal outlet obstruction are presented. They exhibited significant increase in anal outlet obstruction patients over the healthy volunteers. There was no significant difference between pelvic floor electromyographic lag time and opening time readings.

Effect of urethral stimulation on vesical contractile activity.

BACKGROUND: We investigated the hypothesis that urethral stimulation effects vesical contraction. METHODS: Vesical pressure response to urethral balloon distension with normal saline in increments of 1 mL was recorded in 26 healthy volunteers (17 men, 9 women; mean age, 36.9 +/- 9.7 SD years) before and after individual anesthetization of the urinary bladder and urethra. Urethral distension was effected by a 6F balloon-ended catheter introduced per urethra. Vesical pressure was measured by means of a microtip catheter. RESULTS: Vesical pressure recorded gradual increase on increase of urethral balloon distension. Bladder response was maintained as long as urethral distension was continuous. The response showed no significant difference when we distended different parts of the male or female urethrae. Urethral distension after individual vesical and urethral anesthetization effected no change in the vesical pressure. CONCLUSIONS: Urethral distension produced a vesical pressure increase that presumably denotes vesical contraction. Vesical contraction on urethral stimulation by distension is suggested to be mediated through a "urethrovesical stimulating reflex" that seems to facilitate vesical contraction. Provided further studies to be performed in this respect, the reflex may prove to be of diagnostic significance in micturition disorders.

Physiological considerations of the morphologic changes of the testicles during erection and ejaculation: a canine study.

PURPOSE: We investigated the hypothesis that testicles and scrotal skin undergo morphologic changes that would serve the mechanism of erection and ejaculation. MATERIALS AND METHODS: Testicular and scrotal skin changes during erection and ejaculation were studied in 9 dogs. Testicular volume was measured by ultrasound, testicular temperature by digital thermometer and testicular vascularity by color duplex Doppler ultrasonography. Dartos muscle activity was studied by electromyography. RESULTS: Testicular volume increased during erection and diminished at ejaculation. Testicular consistency became softer during erection and firmer at ejaculation. During erection and ejaculation the testicles were elevated closer to abdominal wall. Testicular temperature increased in the erectile phase followed by reduction during ejaculation. Doppler ultrasonography recorded increased testicular vascularity during erection and diminished vascularity at ejaculation. A dartos muscle electromyogram exhibited increased activity in the erectile and ejaculatory phases. CONCLUSION: During erection and ejaculation, testicles underwent changes which apparently serve the erectile and ejaculatory functions of penis.

A novel concept for the surgical anatomy of the perineal body.

PURPOSE: Perineal body is considered by investigators as a fibromuscular structure that is the site of insertion of perineal muscles. We investigated the hypothesis that perineal body is the site across which perineal muscles pass uninterrupted from one side to the other. METHODS: Perineal body was studied in 56 cadaveric specimens (46 adults, 10 neonatal deaths) by direct dissection with the help of magnifying loupe, fine surgical instruments, and bright light. RESULTS: Perineal body consisted of three layers: 1) superficial layer, which consisted of fleshy fibers of the external anal sphincter extending across perineal body to become the bulbospongiosus muscle; 2) tendinous extension of superficial transverse perineal muscle crossing perineal body to contralateral superficial transverse perineal muscle, with which it formed a criss-cross pattern; and 3) tendinous fibers of the deep transverse perineal muscle; the fibers crossing perineal body decussated in criss-cross pattern with the contralateral deep transverse perineal muscle. A relation of levator ani or puborectalis muscles to perineal body could not be identified. CONCLUSIONS: Perineal body (central perineal tendon) is not the site of insertion of perineal muscles but the site along which muscle fibers of these muscles and the external anal sphincter pass uninterrupted from one side to the other. Such a free passage from one muscle to the other seems to denote a "digastric pattern" for the perineal muscles. Perineal body is subjected to injury or continuous intra-abdominal pressure variations, which may eventually result in perineocele, enterocele, or sigmoidocele.

The effect of vaginal distension on the female urinary bladder and urethral sphincters.

AIMS: A mention of effect of vaginal distension, as induced by penile thrusting at coitus, on urinary bladder (UB) and urethral sphincters could not be traced in literature. We investigated the hypothesis that, upon vaginal distension, UB undergoes inhibited activity, while external and internal urethral sphincters (IUS) exhibit increased activity in order to guard against urine leakage during coitus. METHODS: Response of UB and external and IUS to vaginal balloon distension was recorded in 28 healthy women (age 35.6+/-3.3 years). A vaginal condom was inflated with air in increments of 50 up to 200 ml, and vesical pressure as well as electromyographic (EMG) activity of external and IUS were registered. The test was repeated after separate anaesthetisation of vagina, UB and external and IUS. RESULTS: On vaginal distension, vesical pressure was reduced in the ratio of expansion of vaginal volume up to a certain capacity, beyond which vesical pressure ceased to decline when distending volume was augmented. Similarly, IUS EMG activity increased progressively on incrementally added vaginal distension up to 150-ml distension, beyond which any further vaginal distension did not produce an additional increase of EMG activity; the external urethral sphincter (EUS) EMG activity showed no response. Vaginal distension, while the vagina, UB and external and IUS had been separately anaesthetised, produced no significant change. CONCLUSION: Vaginal balloon distension seems to effect vesical wall relaxation and increase IUS tone. This appears to provide a mechanism that prevents urine leak during coitus. Vesical and IUS response to vaginal distension are suggested to be mediated through a reflex we term 'vagino-vesicosphincteric reflex', which seems to be evoked by vaginal distension during penile thrusting. The reflex may prove of diagnostic significance in sexual disorders.

The effect of gastric overfilling on the pharyngo-esophageal and lower esophageal sphincter: a possible factor in restricting food intake.

BACKGROUND: How afferent activity in the gut achieves the required ingestion control has not been established. The authors hypothesized that gastric overdistension effects an increase in pharyngo-esophageal and lower esophageal sphincter activity aimed at inhibiting ingestion. MATERIAL/METHODS: The study comprised 16 mongrel dogs. Under anesthesia, one balloon-tipped catheter was placed in the stomach, another within the lower esophageal sphincter (LES), and a third within the pharyngo-esophageal sphincter (PES). The gastric balloon was filled with H(2)O in increments of 10 ml and LES and PES pressures were recorded. The test was repeated after individual gastric, LES, and PES anesthetization. RESULTS: Gastric balloon filling with more than 20 ml of H(2)O showed progressively increasing LES pressure up to 110-120 ml of gastric filling, beyond which the pressure exhibited no further increase upon incrementally increased gastric filling volume. PES pressure increased only with a gastric filling volume exceeding 100-110 ml and continued to increase with increasing gastric filling. Gastric filling as above while the stomach, LES, and PES were separately anesthetized produced no LES or PES pressure response. CONCLUSIONS: LES and PES appear to contract on gastric filling; PES responds only to excess gastric filling. It seems that LES and PES response to gastric filling is mediated through a reflex which the authors call the "gastro-esophagopharyngeal reflex" (GEPR). Changes in the evoked response would indicate a defect in the reflex pathway. GEPR might thus serve as an investigative tool in the diagnosis of gastroesophageal disorders, although further studies are required.

Duodeno-jejunal junction dyssynergia: description of a novel syndrome.

AIM: To investigate the hypothesis that duodeno-jejunal dyssynergia existed at the duodeno-jejunal junction. METHODS: Of 112 patients who complained of epigastric distension and discomfort after meals, we encountered nine patients in whom the duodeno-jejunal junction did not open on duodenal contraction. Seven healthy volunteers were included in the study. A condom which was inserted into the 1st duodenum was filled up to 10 mL with saline in increments of 2 mL and pressure response to duodenal distension was recorded from the duodenum, duodeno-jejunal junction and the jejunum. RESULTS: In healthy volunteers, duodenal distension with 2 and 4 mL did not produce pressure changes, while 6 and up to 10 mL distension effected significant duodenal pressure increase, duodeno-jejunal junction pressure decrease but no jejunal pressure change. In patients, resting pressure and duodeno-jejunal junction and jejunal pressure response to 2 and 4 mL duodenal distension were similar to those of healthy volunteers. Six and up to 10 mL 1st duodenal distension produced significant duodenal and duodeno-jejunal junction pressure increase and no jejunal pressure change. CONCLUSION: Duodeno-jejunal junction failed to open on duodenal contraction, a condition we call 'duodeno-jejunal junction dyssynergia syndrome' which probably leads to stagnation of chyme in the duodenum and explains patients' manifestations.

Electromyographic activity of the anterolateral abdominal wall muscles during rectal filling and evacuation.

BACKGROUND: The role of the anterolateral abdominal wall muscles (AAWMs) at defecation has not received sufficient attention in the literature. We investigated the hypothesis that the AAWMs exhibit increased electromyographic (EMG) activity on rectal distension, which presumably assists in rectal evacuation. MATERIALS AND METHODS: The effect of rectal balloon distension on the AAWMs EMG and on anal and rectal pressure was examined in 23 healthy volunteers (37.2 +/- 9.4 SD years, 14 men, 9 women); this effect was tested before and after rectal and AAWMs anesthetization. RESULTS: The rectal and anal pressures increased gradually upon incremental rectal balloon distension starting at 70 mL balloon distension until, at a mean of 113.6 +/- 5.6 mL, the balloon was expelled to the exterior. The AAWMs showed no EMG activity at rest or on rectal distension up to the time of balloon expulsion when they exhibited significant increase of EMG. This effect was abolished on individual rectal or AAWMs anesthetization but not with saline administration. CONCLUSIONS: AAWMs appear to contract simultaneously with rectal contraction; this action seems to increase the intra-abdominal pressure and assist rectal evacuation. The AAWMs contraction upon rectal contraction appears to be mediated through a reflex, which we call the "recto-abdominal wall reflex". Further studies are required to investigate the role of this reflex in defecation disorders.

The response of the corporal tissue and cavernosus muscles to urethral stimulation: an effect of penile buffeting of the vaginal introitus.

We investigated the hypothesis that urethral stimulation in humans induces sexual response in the form of activation of the corporal tissue and cavernosus muscles through a reflex mechanism. Electromyographic activity of corpora cavernosa (CC), corpus spongiosum (CS), bulbocavernosus (BCM), and ischiocavernosus (ICM) muscles was recorded in 43 healthy volunteers (24 men, 19 women; age, 37.7 +/- 8.2 years) during urethral stimulation. The tests were repeated after individual anesthetization of urethra, CC, CS, BCM, and ICM. During stimulation of the distal urethra, slow wave variables of CC and CS decreased while motor unit action potentials of BCM and ICM increased. Urethral stimulation after individual anesthetization of urethra, CC, CS, BCM, and ICM did not effect significant changes in these structures, but saline administration did. Diminished electromyographic activity of CC and CS with increased activity of BCM and ICM during distal urethral stimulation presumably denotes sinusoidal muscle relaxation of CC and CS and cavernosus muscles' contraction. Sinusoidal muscle relaxation and contraction of cavernosus muscles upon distal urethral stimulation are suggested to be mediated through a reflex that we call the "urethro-corporocavernosal reflex." Sinusoidal and cavernosus muscles' response during coitus appears to effect a degree of tumescence for both male and female partners.