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Purpose: The aim of this study was to investigate the sacral reflex activity at the striated urethral sphincter relaxation by evoking the potential of the bulbocavernosus reflex (BCR)., Methods: 17 normal male subjects were investigated. BCR was elicited by electrical stimulation of dorsal nerve of the penis, and the evoked potential of the BCR (BCR-EP) was recorded by a concentric needle electrode at the periurethral striated muscle. In normal subjects BCR was performed at rest and during voluntary voiding. In 8 of the normal subjects electrical stimulation was increased gradually during voluntary voiding, and changes of BCR-EP were studied. 3 male patients with neurogenic bladder suffering from urinary incontinence caused by involuntary sphincter relaxation (IVSR) were also investigated. In these patients with neurogenic bladder, BCR was performed at rest and during voluntary voiding as well as during involuntary voiding., Results: In the normal subjects stable BCR-EP was elicited at rest and disappeared during voluntary voiding. But a gradually increased larger stimulation clearly demonstrated BCR-EP during voluntary voiding. In 3 patients with neurogenic bladder, stable ECR-EP was elicited at rest. During involuntary voiding caused by IVSR obvious BCR-EP was also elicited, but its amplitude was slightly less than the amplitude of BCR-EP at rest. During voluntary voiding in 2 of the 3 patients BCR-EP was recognized but the amplitude was much less, and in the third patient BCR-EP could not be recognized., Conclusion: BCR-EP was suppressed during voluntary voiding in normal subjects, but insufficiently suppressed in the patients with neurogenic bladder. In these patients BCR-EP during voluntary voiding was suppressed more distinctly than BCR-EP during involuntary voiding due to IVSR. In urodynamic study, the detrusor contraction and the sphincter relaxation were common phenomenon in both voluntary voiding and involuntary voiding, but the difference in the degree of the BCR suppression depended on whether micturition was voluntary or involuntary. It was suggested that the measurement of BCR-EP could distinguish involuntary voiding caused by pathological urethral sphincter relaxation from voluntary voiding.

Non-adrenergic non-cholinergic nerves (NANC) are thought to be important in the relaxation of corpus cavernosum for erectile function. On the other hand, it has been shown that nitric oxide (NO) is synthesized from L-arginine and released by the endothelium of blood vessels and accounts for the activity of endothelium-derived relaxing factor (EDRF). We studied whether electrical field stimulation (EFS) of isolated strips of human corpus cavernosum released NO and whether it could act as a NANC neurotransmitter. Human penile tissue specimens were mounted in an organ bath and the isometric tension recorded. EFS was applied to precontracted strips between two parallel platinum electrodes. Relaxation induced by EFS was not influenced by guanethidine or atropine, but was markedly inhibited by NG-nitro-L-arginine which is an analog of L-arginine that inhibits the conversion of L-arginine to NO, and hemoglobin which is an agent that inhibits the biological actions of NO. Methylene blue which is an inhibitor of cytosolic guanylate cyclase also reduced the relaxation of EFS, but not completely. The inhibitory effect of NG-nitro-L-arginine was reversed by addition of excess L-arginine. Exogenous NO relaxed human corpus cavernosum. The relaxation was only a transient response and concentration-dependent. The profile of responses is similar to that evoked by EFS. Our data clearly demonstrate the release of NO during EFS and the function of NO as a NANC neurotransmitter. Human penile erection may be mediated by NO generated in response to NANC neurotransmission.

The mechanisms of relaxing effect of papaverine on the phenylephrine (10(-6) M)- or the high K+ (30 mM)-induced contracture were studied on the isolated canine corpus cavernosum. Rod shaped preparation of the corpus cavernosum without the tunica albuginea was mounted in a tissue bath, immersed in Tyrode solution and the isometric tension was recorded. Cumulative applications of papaverine (10(-6) approximately 3 x 10(-5) M) relaxed the phenylephrine (10(-6) M)- or the high K+ (30 mM)-induced contracture with a dose-dependent manner. A pretreatment with papaverine (10(-5) approximately 10(-4) M) dose-dependently reduced the magnitude of the phenylephrine (10(-6) M)-induced contracture, more prominently in the tonic than in the phasic component, while reduced that of the high K+ (30 mM)-induced contracture in both components. The relaxing effect of papaverine (5 x 10(-6) M) on the high K+ (30 mM)-induced contracture was antagonized by an increase in extracellular Ca++ concentration. A reintroduction of Ca++ after perfusion of Ca++ free and high K+ (30 mM) solution containing 1 mM EGTA failed to bring about normal contractile activity in the presence of papaverine (10(-4) M), Papaverine, even if its high concentration (10(-4) M), could not completely abolish the transient phasic contraction evoked norepinephrine (10(-5) M) which was abolished by ryanodine (3 x 10(-6) M), in Ca++ free solution. Isoproterenol (10(-8) approximately 10(-6) M) or dibutyryl cyclic-AMP (10(-5) approximately 10(-3) M) relaxed the phenylephrine (10(-6) M)- and the high K+ (30 mM)-induced contracture.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous monitoring of penile rigidity and tumescence has been proved to be of use for accurate diagnosis of erectile impotence, since it provides objective recording of penile rigidity as well as circumferential expansion. Prior to clinical use of this procedure in Japan, a study was performed to clarify normal features of nocturnal penile tumescence of Japanese and to ensure safety of this procedure. The subjects consisted of 16 normal volunteers, aged from 24 to 44 years. With fully informed consent of the volunteers, nocturnal penile rigidity and circumferential expansion were simultaneously measured for three consecutive nights by means of RigiScan at the base of the penis (base) and at about five millimeters proximal to the coronary sulcus (tip). The minimum circumference of the penis was 62.7 +/- 4.6 mm (mean +/- SD) at the tip and 65.4 +/- 9.3 mm at the base. The maximum circumference, which meant full erection in the normal volunteers, was 102.5 +/- 14.2 mm at the tip and 108.6 +/- 14.7 mm at the base. The mean duration of tumescence, i.e. circumference expansion more than 10 mm, was 23.0 +/- 6.9 minutes at the tip and 38.3 +/- 12.0 minutes at the base. The mean rate of episodes of circumference expansion more than 10 mm was 0.75 +/- 0.27 per hour at the tip and 0.70 +/- 0.26 per hour at the base. The maximum rigidity lasting more than 10 minutes was 82.9 +/- 10.1% at the tip and 85.4 +/- 8.4% at the base.(ABSTRACT TRUNCATED AT 250 WORDS)

By continuous and simultaneous recording of nocturnal penile rigidity and circumferential expansion (tumescence), nocturnal penile rigidity and tumescence have been classified into 6 patterns: normal, dissociation, uncoupling, short episode, low amplitude and flat trace. The monitoring will be helpful to diagnose underlying disorders involving erectile impotence, if the pattern of nocturnal penile rigidity and tumescence are related with the disorders. This study analyzed the relationship between the pattern of nocturnal penile rigidity and tumescence and associated disorders in 105 patients with erectile impotence. Of 15 patients with central nervous system disorders, 9 (60%) had a pattern of short episode of rigidity. In 29 patients with cardiovascular disorders, the patterns of dissociation, low amplitude and flat trace were the main findings and observed in 41, 41, 35% of the group, respectively. No patients with diabetes mellitus showed normal pattern. Although the group of non insulin dependent diabetes mellitus (21 patients) had various patterns of rigidity and tumescence, the insulin dependent group (14 patients) mainly showed patterns of low amplitude (21%) and/or flat trace (71%). The continuous and simultaneous monitoring of penile rigidity and tumescence will be helpful, with an integral analysis of its pattern and other examinations, for accurate diagnosis of underlying disorders of organic impotence, besides for differentiation of organic impotence from psychogenic one.

To evaluate the factors contributing to the decline in erectile function with age, we performed measurement of nocturnal penile tumescence (NPT) and penile vascular examinations in 407 men. The following results were obtained. 1) The penile circumferential increment during NPT measured by an erectometer was gradually decreased with age, especially markedly after 60 years of age. The percentage of subjects in whom the NPT was less than 10 mm increased with age: 2.7% in the 5th decade, 7.1% in the 6th decade, 16.7% in the 7th decade and 29.1% in the 8th decade. These findings indicate that the incidence of organic erectile dysfunction increased with age. 2) To evaluate the penile vascular status, measurement of penile blood pressure index (PBPI) and papaverine test were performed. The mean PBPI values were significantly decreased in the subjects over 70 years of age. The percentage of subjects having good response to papaverine injection obviously decreased with age: 66.7% between 50 to 59 years, 48.6% between 60 to 69 years, and 15.8% of over 70 years. All subjects in whom the NPT was less than 10 mm showed either a low PBPI level of less than 0.6 or an incomplete response to papaverine injection. These results suggest that penile vascular impairment plays a major role in the age-associated decline in erectile function. 3) We investigated the relationship between cigarette smoking and penile vascular impairment. Smokers showed not only lower PBPI values but higher incidence of the incomplete response to papaverine injection than nonsmokers. Therefore, it is considered that cigarette smoking is a significant risk factor in the erectile dysfunction that occurred in the aged.

Evoked response of bulbocavernosus reflex was taken in 8 normal control individuals and in 15 abnormal voiding patients (8 benign prostatic hyperplasia, 4 diabetic neuropathy, 3 supranuclear neurogenic bladder). the latency in control group showed 31.5 +/- 5.0 msec duration after penile stimulation and 65.4 +/- 11.0 msec duration after posterior urethral stimulation. The latency in diabetic neuropathy group was obviously prolonged but not that in the supranuclear neurogenic bladder group. This modern neurophysiological electrostimulation method provides simple and accurate information of bulbocavernosus reflex.