Actions of 3-morpholinosydnonimin (SIN-1) on rabbit isolated penile erectile tissue

The effects of the NO-donor 3-morpholinosydnonimin (SIN-1) on isometric tension, cyclic guanosine 3',5'-monophosphate (cyclic GMP) accumulation and neuronal release of 3H-noradrenaline were investigated in rabbit isolated corpus cavernosum (CC), and compared to the actions of sodium nitroprusside (SNP) and the cyclic GMP-specific phosphodiesterase inhibitor zaprinast. SIN-1, zaprinast and SNP concentration dependently relaxed rabbit CC preparations contracted by 1 microM. phenylephrine. All the drugs were highly effective, and the order of potency was SNP > zaprinast > SIN-1. SIN-1 had a biphasic effect on contractions evoked by electrical field stimulation of nerves: at low concentrations (1 and 10 microM.), SIN-1 inhibited the contractions, while at concentrations > or = 100 microM., the contractions were again increased. There were no changes in baseline tension. Electrically evoked contractions were inhibited by zaprinast in a concentration-dependent manner. Compared with controls, 1 mM. SIN-1 caused a significant (p < 0.05) increase in both the basal efflux and in the electrically induced release of 3H from CC preparations incubated with 3H-noradrenaline. SIN-1, zaprinast and SNP increased tissue levels of cyclic GMP. There was no positive correlation between cyclic GMP accumulation and the relaxant effects of the drugs. The effects of SIN-1 and SNP on the tissue content of cyclic GMP were not significantly affected by methylene blue, an inhibitor of soluble guanylate cyclase. It may be concluded that SIN-1, zaprinast and SNP are effective in relaxing isolated penile erectile tissue, and this effect is associated with an increase in the tissue content of cyclic GMP via pathways not sensitive to methylene blue. However, additional mechanisms beside stimulation of adrenergic neurotransmission and activation of guanylate cyclase in the smooth muscle cell seem to participate in the action of SIN-1 on rabbit penile erectile tissue.

Stereologic studies on collagen in bovine articular cartilage

In an ultrastructural stereologic study on bovine articular cartilage we found that collagen volume density increased with increasing distance from the joint surface and from the chondrocyte. These results not only corroborate previous biomechanical data of a vertical stiffness gradient, but they also suggest that the mechanical forces are unevenly distributed horizontally. On the other hand, although mean collagen fibril diameter showed large differences between the interterritorial compartments of the three zones, there was a population of slender fibrils in all zones and compartments. Since the coarser fibrils provide the high tensile strength (Nimni 1988), the role of the slender fibrils may be to enhance the deformability of the tissue. Moreover, in spite of substantial differences in mean fibril diameter, collagen surface densities were in the same order of magnitude in the territorial and interterritorial compartments, and only slightly lower in the pericellular compartments. The surface parameter may be important for specific molecular interactions. The collagen fibrils have different polarity, i.e. the direction of the fibrils appears to be parallel and antiparallel, about 50% running in each direction. This, together with the very high length/diameter ratio (Clark 1985), may indicate that each fibril is assembled by the concerted action of many cells. The characteristic properties of articular cartilage depend on interactions between its macromolecular components, and the present quantitative data form a basis for discussions on the specificity and regulation of such interactions.

Contractions induced by angiotensin I, angiotensin II and bradykinin in isolated smooth muscle from the human detrusor

In isolated human detrusor preparations angiotensin (At)II 10(-9)-10(-5) M caused concentration-dependent contractions. The contractile effect was immediate, and had an amplitude which at the highest concentration used, 10(-5) M, reached 103 +/- 16% of the mean contraction produced by K+ 124 mM (27.6 +/- 1.4 mN). The AtII effect was completely blocked by saralasin 10(-6) M, but was not affected by pre-treatment of the preparations with captopril or enalaprilate. There was a marked tachyphylaxis to the actions of the peptide. AtI (10(-8)-10(-5) M) also caused contractions which were rapidly developing, and subject to a marked tachyphylaxis. At a concentration of 10(-5) M, the mean amplitude was 66 +/- 9% of the K(+)-induced contraction. The contractions were blocked by saralasin 10(-6) M, but not by captopril or enalaprilate 10(-5) M. In contrast, contractions produced by AtI in rabbit mesenteric arteries were practically abolished by the angiotensin converting enzyme (ACE) inhibitors. The contractions induced by both AtI and AtII were practically abolished after pre-treatment in a nominally calcium-free Krebs solution. However, blockade of L-type calcium channels by nifedipine 10(-6) M reduced the responses to both AtI 10(-6) M (by 38 +/- 4%) and AtII 10(-6) M (by 39 +/- 7%), but never abolished the contractions. Bradykinin (Bk; 3 x 10(-8)-10(-5) M) had a contractile effect in detrusor preparations which varied widely between strips. At a concentration of 3 x 10(-6) M, a maximum was reached amounting to 30 +/- 10% of the K(+)-induced contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term anorectal function in imperforate anus treated by a posterior sagittal anorectoplasty: manometric investigation

Thirty imperforate anus patients were investigated by anorectal manometry 5 to 10 years after a posterior sagittal anorectoplasty. Anal resting tone (ART) and anal squeezing pressure (ASP) were subnormal in most patients. Rectal volume (RV) and sensation to balloon distension were within the normal range. Rectoanal reflex inhibition was demonstrated in 9 of 30 patients. Soiling was more common in patients with a very low ART (less than 40 cm H2O) and a low ASP (less than 100 cm H2O). Constipation was more common in patients with a large RV (greater than 150 mL). Still, the correlation to clinical results was incomplete. As regards to the correlation to type of malformation the rectal atresia patients showed near normal results. The vestibular fistula patients were next in results showing rectoanal reflex inhibition in 5/6 patients. There was no difference in the results between bulbar and prostatic fistula patients.

Sacrococcygeal teratoma in Sweden between 1978 and 1989: long-term functional results

Thirty-four patients operated with sacrococcygeal teratoma in Sweden between 1978 and 1989 were reviewed. Twenty-five children were available for functional follow-up. The patients and their parents were interviewed for bowel and micturition habits. Fourteen patients from this number were subjected to anorectal manometry (56%). Fifteen children reported normal bowel habits (60%). In 10 patients (40%) soiling was observed. However, four of them were under 3 years of age and wearing diapers, which made the functional evaluation difficult. The manometries showed normal and resting tone and squeezing pressures in 10 patients and subnormal values in four patients who also had soiling problems. All investigated children showed normal rectoanal inhibition reflex. Twenty-one patients reported normal micturition, in four (16%) urinary incontinence was recorded. Two of the latter children required intermittent clean catheterization, one was on medication and the last one lives without any treatment. No difference in functional outcome was noted between patients with intrapelvic or extrapelvic tumor location. Retrospectively, it is not possible to know whether the observed functional outcome is due to tumor growth or the result of surgery. Preoperative clinical investigation and in some cases anorectal manometry and cystometry could theoretically resolve this problem.

Characterization of inhibitory neurotransmission in the isolated corpus cavernosum from rabbit and man

1. NG-nitro-L-arginine (L-NOARG, 10(-4) M), an inhibitor of nitric oxide (NO) synthesis, had no contractile effect on isolated preparations of rabbit and human corpus cavernosum at baseline tension, but increased tension in preparations contracted by noradrenaline (rabbit 10(-5) M, man 3 x 10(-7)-3 x 10(-6) M) or K+ (rabbit 60 mM). 2. Electrical field stimulation (supramaximal voltage, 0.8 ms pulses, 5 s train duration, 0.5-35 Hz) of rabbit and human corpus cavernosum preparations contracted by noradrenaline (rabbit 10(-5) M, man 3 x 10(-6) M) or endothelin-1 (rabbit 10(-8) M) produced relaxations that were sensitive to tetrodotoxin (10(-6) M), and dependent on the frequency and number of pulses delivered. L-NOARG (10(-6)-10(-4) M), but not NG-nitro-D-arginine (D-NOARG, 10(-6)-10(-4) M), inhibited electrically induced relaxations in a concentration-dependent manner, and at 10(-4) M the relaxations were virtually abolished. L-Arginine (10(-3) M), but not D-arginine (10(-3) M), partly reversed the inhibitory effect of L-NOARG (10(-4) M). In rabbit corpus cavernosum preparations, as with Methylene Blue (3 x 10(-5) M), an inhibitor of the soluble guanylate cyclase, and haemoglobin (10(-5) M), sequestering NO in the extracellular space, significantly reduced electrically evoked relaxations. Scopolamine (10(-6) M) had little or no effect on relaxations induced by electrical field stimulation. 3. Preparations of rabbit and human corpus cavernosum contracted by noradrenaline (rabbit 10(-5) M, man 3 x 10(-6) M) were relaxed by carbachol (10(-9)-10(-4) M) in a concentration-dependent manner. Scopolamine (10(-6) M) and L-NOARG (10(-4) M) abolished, and Methylene Blue (3 x 10(-5) M) and haemoglobin (10(-5) M) greatly reduced, the carbachol-induced relaxation, while D-NOARG (10(-4) M) had no significant effect. 4. In rabbit corpus cavernosum preparations contracted by noradrenaline (10(-5) M), L-NOARG (10(-4) M) had no significant effect on relaxations induced by vasoactive intestinal polypeptide (10(-6) M). 5. SIN-1 (3-morpholino-sydnonimin hydrochloride, 10(-8)-3 x 10(-4) M), which spontaneously liberates NO, relaxed preparations of rabbit and human corpus cavernosum contracted by noradrenaline (rabbit 10(-5) M, man 3 x 10(-6) M) or endothelin-1 (rabbit 10(-8) M, man 3 x 10(-9) M) in a concentration-dependent way.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of pinacidil on detrusor instability in men with bladder outlet obstruction

In a double-blind, crossover study the effect of the potassium channel opener pinacidil (N''-cyano-N'4-pyridyl-N-1,2,2-trimethylpropylguanidine monohydrate) at 25 mg. per day was evaluated in 10 patients with detrusor instability and bladder outlet obstruction. Nine patients completed the study: in 7 pinacidil was without significant effect on urodynamic variables and in 2 detrusor instability was not found at the end of the pinacidil period. Maximum urinary flow, frequency and nocturia were unchanged during pinacidil treatment, compared to the initial test and the placebo period. There was a significant decrease in standing blood pressure but heart rate was stable throughout the study. No patient experienced distinct symptomatic improvement or side effects during pinacidil treatment. The results suggest that pinacidil at the dosage given is not effective for treatment of unstable detrusor contractions associated with bladder outflow obstruction.

Studies on binding sites, contents, and effects of AVP in isolated bladder and urethra from rabbits and humans

The binding sites, contents, and effects of arginine vasopressin (AVP) were studied in isolated bladder and urethral preparations from rabbits and humans. In all tissues, higher levels of AVP-like immunoreactivity (AVP-LI) were detected than those normally found in plasma. Radioligand membrane binding studies using [3H]AVP as the ligand revealed the existence of a single population of binding sites in the rabbit bladder, and displacement experiments indicated that the receptor was of the V1 subtype. By autoradiography, [3H]AVP binding sites in the rabbit bladder were shown to be located on both circularly and longitudinally oriented smooth muscle cells, as well as in the submucosa at the part adjacent to the urothelium. In the rabbit urethra, the binding sites were confined mainly to the circular smooth muscle layer. Neither radioligand membrane binding studies nor autoradiography revealed any specific [3H]AVP binding sites in the human bladder. AVP contracted rabbit bladder and urethral preparations concentration dependently. The contractions were inhibited by the V1-receptor selective antagonist A16 in a noncompetitive manner. However, A16 had no effects on contractions elicited by electrical-field stimulation. In preparations of the human bladder and urethra, AVP in concentrations up to 10(-5) M did not have any contractile effects. These results suggest that in the rabbit and human lower urinary tract, AVP-LI is synthesized locally and/or extracted from the circulation. It is unlikely that AVP is directly involved in the neurotransmission in these tissues, although in the rabbit bladder and urethra a modulatory role cannot be excluded.

Muscarinic receptor stimulation of phosphoinositide hydrolysis in the human isolated urinary bladder

The stimulatory action of carbachol and acetylcholine (ACh) on phosphoinositide turnover, as well as their contractile effects, were investigated in human isolated detrusor muscle. Carbachol, and ACh in combination with 10(-7) M physostigmine, induced increases in phosphoinositide turnover. However, at all the concentrations tested, carbachol was more effective than ACh (plus physostigmine), and at the highest concentration used (10(-4) M), the difference was significant (p less than 0.05). Also in a Ca(2+)-free medium containing the chelator EGTA (10(-4) M), both agonists (10(-4) M) induced small but distinct increases in phosphoinositide breakdown. Carbachol and ACh contracted the detrusor preparations concentration-dependently, and the responses were almost identical when ACh was combined with 10(-7) M physostigmine. In Ca(2+)-free medium the agonists elicited a moderate but concentration-dependent contractile response at high concentrations. The results show that muscarinic receptor agonists stimulate phosphoinositide turnover in the human bladder. Possibly, this effect is coupled to multiple muscarinic receptor subtypes. More studies are required to elucidate to what extent phosphoinositide breakdown participates in the contractile activation of this tissue.

Pre- and postjunctional effects of some prostanoids in human isolated vas deferens

The effects of prostaglandin (PG) E1, PGE2, the thromboxane A2 analogue U-44069, and the prostacyclin derivative iloprost were studied on isometric contractions induced by norepinephrine (NE) and by electrical field stimulation of nerves in isolated preparations of the human vas deferens. The effects of these agents on the electrically induced release of 3H from preparations preincubated with [3H]NE were also investigated. PGE1 and PGE2 inhibited the electrically induced contractions concentration dependently. U-44069 augmented the contractions without affecting baseline tension, and in preparations where the contractions had been inhibited by PGE1 or PGE2, U-44069 restored the contractions almost to starting levels. The thromboxane A2-receptor antagonist BM 13505, having no effect or inhibitory effects on electrically induced contractions, abolished the stimulatory effect of U-44069. Contractions induced by exogenous NE were augmented by U-44069, whereas PGE1 and BM 13505 were without effects. The electrically induced release of 3H was inhibited by PGE1 and PGE2 in a concentration-dependent manner, whereas U-44069 and BM 13505 increased the release of 3H. Furthermore, the inhibitory effect of PGE1 on 3H release was partly counteracted by U-44069. Iloprost had no significant effect on electrically induced contractions or on 3H release. These results suggest that, in the human vas deferens, thromboxane A2 augments contractions predominantly through a postjunctional site of action, whereas PGs of the E type have a prejunctional inhibitory effect. In addition, the pre- and post-junctional effect profiles of U-44069 and BM 13505 suggest that there may be more than one thromboxane receptor.

Cystourethrometric findings in patients with detubularized right colonic segment for bladder replacement

Urodynamic evaluation was performed in 13 men 4 to 18 months after cystoprostatectomy and bladder replacement using a detubularized right colonic segment. All patients are continent by day and only 3 are incontinent during the night to a degree that necessitates use of a condom catheter. Two patients awaken every 2 to 3 hours to void and the remainder have nocturia comparable to normal men of their age. The residual volume was 0 to 70 ml. The urethral closure pressure was normal, and in 3 patients studied preoperatively and postoperatively no significant change was observed other than shortening of the profile length. Maximal flow rates were normal although the pattern was intermittent. In 2 patients no cystoplasty contractions were recorded and in all but 2 patients the amplitude of the contractions was less than 40 cm. water. Simultaneous bladder and urethral pressure recordings during bladder filling demonstrated no change in urethral pressure in 10 patients. Although creation of a reservoir with a low pressure and careful preservation of the infraprostatic urethra are important for continence in these patients, we believe that the absence of normal sacral route reflexes after cystoprostatectomy is an important contributing cause to nocturnal incontinence.

Effects of the alpha 1-adrenoceptor antagonist R-(-)-YM12617 on isolated human penile erectile tissue and vas deferens

The effects of the selective alpha 1-adrenoceptor antagonist, R-(-)-YM12617 (5-[2-[[2-(0-ethoxyphenoxy)ethyl]amino] propyl]-2-methoxybenzenesulphonamide HCl), were investigated in isolated human corpus spongiosum, corpus cavernosum, and vas deferens. R-(-)-YM12617 concentration dependently and competitively inhibited contractions induced by noradrenaline in human penile erectile tissue (pA2 value in corpus spongiosum = 9.92), and the drug was approximately 12 times more potent than prazosin (pA2 value = 8.83). In the vas deferens, R-(-)-YM12617 and prazosin inhibited electrically induced contractions concentration dependently, and abolished the contractions at 10(-6) and 10(-5) M, respectively. The -log IC50 values for R-(-)-YM1261 and prazosin were 8.46 and 7.50, respectively. It is concluded that R-(-)-YM12617 is a potent inhibitor of alpha 1-adrenoceptors in human penile erectile tissues and vas deferens, and that the drug, if injected intracavernosally, may be useful for the treatment of penile erectile dysfunction.

Does the distal rectal muscle in anorectal malformations have the functional properties of a sphincter?

Smooth muscle strips from the distal rectum of 11 patients who underwent surgery for imperforate anus and cloacal malformations, were studied in vitro to assess the motility response to electrical field stimulations (EFS) and to pharmacological stimulation with adrenergic and cholinergic agonists. EFS induced a nonadrenergic, noncholinergic inhibition in most strips. Acetylcholine caused either a modest contraction, no response, or a relaxation. Following atropine administration, acetylcholine caused a nonadrenergic and tetrodotoxin-resistant relaxation. The alpha-adrenergic agonist phenylephrine induced contractions in all strips. The response was abolished by alpha-adrenoceptor blockade with phentolamine, but was resistant to atropine and tetrodotoxin. beta-Adrenergic stimulation caused a relaxation that was abolished by propranolol. Function of the distal rectal smooth muscle, resected during correction of anorectal malformations, shows similarities to the function reported previously on normal anal smooth muscle evaluated in vitro.

K(+)-channel openers for relaxation of isolated penile erectile tissue from rabbit

The effects of the K(+)-channel openers (KCOs) cromakalim (BRL 34915) and pinacidil were investigated and compared with those of papaverine on isolated corpus cavernosum from rabbit. Preparations were mounted in organ baths and isometric tension was recorded. Spontaneous contractile activity was effectively abolished by the KCOs tested, cromakalim being the most potent of them. The KCOs concentration-dependently and effectively depressed electrically induced contractions and also contractions induced by exogenously applied noradrenaline and by low (less than or equal to 20 mM) concentrations of K+. Cromakalim was three to four times more potent than pinacidil. Pinacidil and cromakalim were shown to cause increases in the efflux of 86Rb from preloaded cavernous tissue. Papaverine also effectively depressed spontaneous contractile activity, and contractions evoked by electrical stimulation and noradrenaline. It had a potency 19 to 36 times lower than that of cromakalim. However, papaverine did not increase 86Rb efflux from preloaded tissue. The results show that cromakalim and pinacidil effectively relax penile erectile tissue, probably by the opening of K(+)-channels and subsequent hyperpolarization. Further investigations on human material seems motivated in order to elucidate if the principle of K(+)-channel opening offers any therapeutic advantages to other drugs in the diagnosis and treatment of penile erectile dysfunction.

Prostaglandin E2 binding sites in human renal tissue: characterization and localization by radioligand binding and autoradiography

The prostaglandin E2 (PGE2) binding site in human kidney was characterized in membrane preparations from cortex, outer medulla and inner medulla using radioligand binding techniques. The localization of the binding sites for [3H]PGE2 was visualized autoradiographically. In the membrane suspensions, the highest level of specific [3H]PGE2 binding was detected in the outer medulla (Bmax = 335 +/- 28 fmol mg-1 protein) followed by the inner medulla (Bmax = 258 +/- 21 fmol mg-1 protein) and the cortex (Bmax = 143 +/- 22 fmol mg-1 protein). The binding was of high affinity with KD values between 3.7 and 6.2 nM in the various regions. Unlabelled prostaglandins competed for the [3H]PGE2 binding sites in the following rank order of potency: PGE2 approximately PGE1 greater than PGF2 alpha approximately PGA2 greater than PGB2 greater than PGI2 approximately PGD2. Autoradiographs revealed that a high density of [3H]PGE2 (2 nM) binding sites were located on the distal tubule, particularly on the thick ascending limbs of Henle. Lower densities of [3H]PGE2 binding sites were found on the medullary collecting ducts and possibly on the thin loops of Henle. In contrast, no specific [3H]PGE2 binding could be found on the proximal tubule, glomeruli or on blood vessels. This distribution is in accordance with the assumed site of action for the salt and water regulatory function of PGE2.

Actions of endothelin on isolated corpus cavernosum from rabbit and man

The effects of endothelin, a vasoconstrictor peptide produced by vascular endothelial cells, were investigated in isolated rabbit and human corpus cavernosum (CC). Preparations from both rabbit and man were potently contracted by endothelin in a concentration-dependent manner. The contractions developed slowly, could not be reversed despite frequent washings, and were only partly inhibited by the Ca2+ channel blocker nimodipine. Even in Ca2(+)-free medium containing the chelator EGTA a small contractile component persisted. In rabbit CC, the contractions in Ca2(+)-free medium were not affected by nimodipine, the Ca2(-)-channel agonist BAY K 86(44), or by depletion of intracellular Ca2(+) stores sensitive to noradrenaline (NA) and caffeine, but were almost abolished by the protein kinase C inhibitor H7. In both rabbit and man, carbachol and vasoactive intestinal polypeptide concentration-dependently relaxed preparations contracted by endothelin. The relaxations induced by carbachol were antagonized by atropine. Endothelin enhanced concentration-dependently the contractions induced by exogenously applied NA in rabbit CC. The enhancement was more pronounced at low concentrations of NA. This study shows that endothelin potently contracts isolated penile erectile tissue. The contraction seems to be mediated mainly by influx of Ca2+ through the cell membrane, which partly occurs through a pathway other than voltage-operated calcium channels. However, involvement of other mechanisms cannot be excluded. The results suggest that endothelin can play a role in penile erectile mechanisms.

Effects of pinacidil on isolated human corpus cavernosum penis

Intracavernous injection of vasoactive agents causing vasodilatation is widely recognized in the diagnosis and treatment of erectile dysfunction. However, papaverine, the drug most commonly used for this purpose, may produce priapism and fibrotic lesions, and alternatives without these disadvantages are desirable. In this study we investigated the effects of pinacidil, a vasodilator drug supposed to act through the opening of K+ channels, on isolated human corpus cavernosum penis. Besides abolishing spontaneous contractile activity, pinacidil effectively relaxed preparations precontracted by noradrenaline 10(-6) M and inhibited contractions induced by electrical field stimulation of nerves. Furthermore, pinacidil depressed contractions induced by low-K+ solutions (less than or equal to 20 mM) and concentration-dependently increased the efflux of 86Rb from preloaded tissue. The results suggest that pinacidil is effective in relaxing isolated human erectile tissue, probably by way of increased K+ permeability and subsequent hyperpolarization. Clinical testing seems justified in order to find out if K(+)-channel openers can be used in the pharmacological treatment of impotence.

Influence of age, fat cell weight, and obesity on O2 consumption of human adipose tissue

The oxygen consumption of human adipose tissue (AT) was determined in 53 adults, lean and obese, and in nine lean boys. The oxygen consumption was positively related to fat cell weight and negatively to age and degree of obesity. Men and women did not differ with respect to oxygen consumption of AT. The positive relationship between oxygen consumption per cell and fat cell size was also demonstrated in size-separated cells from the same donors. Expressed per cell the oxygen consumption was higher in fat cells from obese than in cells from lean subjects, but expressed per gram of tissue the opposite result was found. The oxygen consumption of the total AT organ was higher in obese than in lean subjects. The energy expenditure of AT constituted approximately 4% of the estimated 24-h energy expenditure in both groups. It is concluded that obese subjects do not maintain their obesity because of a reduced energy expenditure of the total AT (or of the total body). After a partial weight reduction in five subjects, the energy metabolism tended to change in direction toward the conditions seen in lean subjects. However, it is still an open question whether the observed energy metabolic aberrations of obese human AT are only secondary to the obese state or partly primary and thus of etiological importance.