Characterization of immunoreactive arginine vasopressin (AVP) in and effects of AVP on isolated human penile erectile tissues

Arginine vasopressin (AVP), which has been shown to have a marked contractant effect on human penile erectile tissues, particularly the corpus spongiosum (CS), was demonstrated to occur in these tissues. Out of nine CS samples, eight contained vasopressin-like immunoreactivity in concentrations ranging from 3.5 to 107.2 fmol./gm. wet weight. These amounts suggest that the hormone is taken up and/or synthesized locally. The effects of four different vasopressin antagonists were characterized on human CS strips, and they were found to effectively inhibit the contractile response to exogenous AVP. However, none of these antagonists had any effects on electrically induced contractions in penile erectile tissues. These results do not favour the view that AVP is released on electrical stimulation in amounts that contract the erectile tissues. Whether or not the peptide is involved in the mechanisms controlling penile erection remains unclear.     

Effects of the antidepressant St. John's wort (Hypericum perforatum) on rat and human vas deferens contractility

PURPOSE: Since sexual dysfunction related to vas deferens smooth muscle contractility is a possible side effect of St. John's wort (SJW) (Hypericum perforatum) we evaluated the effect of this herbal antidepressant on rat and human vas deferens contractility. MATERIALS AND METHODS: The effect of SJW was evaluated on contractions induced by electrical field stimulation or exogenous agonists (alpha,beta-methylene adenosine triphosphate and phenylephrine) in isolated rat and human vas deferens. RESULTS: SJW (1 to 300 microM) decreased in a concentration dependent manner the amplitude of electrical field stimulation and agonist induced contractions with the same potency, suggesting direct inhibition of rat vas deferens smooth muscle. Of the chemical constituents of SJW tested hyperforin but not hypericin or the flavonoids quercitrin, rutin and kaempferol inhibited phenylephrine induced contractions. SJW and hyperforin also inhibited phenylephrine induced contractions in human vas deferens CONCLUSIONS: The results of our study demonstrate that SJW directly inhibits rat and human vas deferens contractility. If confirmed in vivo, these results suggest that SJW might affect sexual function in humans. These results might explain delayed ejaculation described in patients receiving SJW.     

Calcium channel blockade and contractile responses in the isolated human vas deferens

The effects of removal of extracellular calcium and of the calcium channel blockers nifedipine, verapamil and diltiazem were studied on contractions induced by electrical field stimulation and high K+-solution in isolated preparations of the human vas deferens. Electrically induced contractions were blocked by tetrodotoxin and alpha-adrenoceptor blockade. They were abolished in calcium-deficient medium, and suppressed by the calcium channel blockers in the order of potency nifedipine greater than verapamil greater than diltiazem. The maximum blocking effect of nifedipine was approximately 40%. All the blockers practically abolished K+-induced contractions. It is concluded that even if the contractile response of the human vas deferens to electrical stimulation is dependent on extracellular calcium, calcium channel blockers seem to have only a limited effect on this contraction and their capability of impairing the function of the vas deferens in patients is questioned.     

Effect of extracellular Mg concentration on electrically induced contractions of rat vas deferens in vitro

Contraction of smooth muscles of the vas deferens plays an important role in the propulsion of sperm into the pelvic urethra. This study examined the influence of external Mg2+ concentration on reactivity of the rat vas deferens to electrical stimulation in vitro. Vasa deferentia isolated from adult male rats were set up in tissue baths containing physiological salt solution at 37 degrees C and were stimulated electrically. Thereafter, increasing concentrations of Mg2+ were added to the bath and their effects on electrically evoked contractions were recorded. The effect of external Mg2+ depletion on evoked contractions was also examined. External Mg2+ depletion enhanced the contractile response to electrical stimulation while increasing external Mg2+ concentration inhibited the contractions. The inhibitory effect of Mg2+ was partially reversed by increasing extracellular Ca2+ concentration and was not additive with nifedipine. The results indicate that reactivity of the vas deferens to electrical stimulation is modulated by extracellular Mg2+ concentration. The possible relevance of these data to sperm transport through the vas deferens is discussed.     

Analysis of the contractions evoked by sympathetic nerve stimulation, and thermal effect on the guinea-pig vas deferens--study as a model for the thermotherapy of benign prostatic hyperplasia

BACKGROUND: The present study was designed to investigate the mechanism of thermotherapy on benign prostatic hyperplasia (BPH), using the guinea-pig vas deferens as a model for BPH. The components of contractions elicited by electrical field stimulation and nicotine were analyzed, and the thermal effect on the vas deferens was examined. METHODS: The vas deferens was dissected, suspended vertically through two silver ring electrodes, and attached to an isometric transducer. The electrical stimulation of 10 constant current pulses (10 mA) with 0.3 msec in duration of 5, 10, and 40 Hz was achieved under air-gap condition. Drugs were added directly to a 5 ml Magnus tube containing Tyrode solution (36 degrees C) gassed with a 95% O2-5% CO2 mixture. The components of contractions evoked by electrical stimulation and nicotine were investigated by tetrodotoxin (TTX), and blocking agents of alpha 1-adrenoceptors and/or purinoceptors. Thermal effect on electrically evoked contractions was examined at incubation temperature of 25 degrees C (control), 43 degrees C, 45 degrees C, 46 degrees C and 47 degrees C for 1 hour. RESULTS: Nicotine (200 microM) elicited biphasic contractions, which were triggered by corelease of noradrenaline (NA) and ATP (N-ATP) from sympathetic nerve terminals by activation of prejunctional nicotine receptors. NA and N-ATP caused the corresponding contractions, alpha 1 and N-ATP components, respectively. Combined application of prazosin (1 microM) and suramin (50 microM) abolished these contractions. Activation of post-junctional alpha 1-adrenoceptors by NA caused release of ATP from muscle cells to produce the contraction (alpha 1-ATP component), which was sensitive to both suramin and prazosin. N-ATP and alpha 1 components attributed to fast and slow part of the contraction, respectively. Electrical field stimulation caused biphasic contractions which consisted of both neurogenic (TTX-sensitive) and non-neurogenic (TTX-insensitive) components. An increase in stimulation frequency (5 to 40 Hz) increased the neurogenic components, which contained alpha 1 and N-ATP components, as well as the case of nicotine. The non-neurogenic components consisted of alpha 1-ATP, muscle-derived ATP (m-ATP) and unknown substance 'X' components. Nifedipine (10 microM). L-type Ca2+ channel blocker, markedly reduced the contractions induced by bath applied phenylephrine (alpha 1-agonist, 100 microM) but only partially blocked the contractions produced by bath applied ATP (500 microM). The contractile force in amplitude and neurogenic components induced by electrical field stimulation did not change at 43 degrees C, but both declined significantly above 45 degrees C. The neurogenic components at 45 degrees C and 46 degrees C were suppressed to 22 +/- 6% and 14 +/- 3% (mean +/- SD) of control, respectively. All the contractile responses were abolished at 47 degrees C. CONCLUSION: The contractions of the guinea-pig vas deferens evoked by electrical field stimulation consisted of alpha 1, N-ATP, alpha 1-ATP, m-ATP and X components. Sympathetic nerve fibers in the muscles were completely inactivated by thermal exposure at 47 degrees C for 1 hour. The results suggest that the minimal temperature for thermotherapy of BPH should be 47 degrees C.     

Stimulating and potentiating effects of sodium nitroprusside on the guinea-pig vas deferens and their comparison with the effects on the portal vein and the taenia coli

The effects of sodium nitroprusside on the electrical and mechanical properties of the guinea-pig vas deferens were studied and compared with those on the portal vein and the taenia coli. Sodium nitroprusside at concentrations higher than 0.5 mM caused depolarization of the membrane of the vas deferens and initiated spontaneous contractions, while spontaneous contractions of the portal vein were blocked by similar concentration of the drug. Noradrenaline- and carbachol-induced contractions of the vas deferens were markedly potentiated by sodium nitroprusside, whereas the noradrenaline-induced contraction of the portal vein was suppressed by the same concentration of the drug. Increasing the K+ concentration by 15 to 30 mM caused a similar potentiation of the contraction by noradrenaline or carbachol in the vas deferens. When sodium nitroprusside was applied during the course of noradrenaline- or carbachol-induced contracture, contraction was observed in the vas deferens, while relaxation was induced in the portal vein and taenia coli. In either case, however, the addition of Ca caused a relaxation of the preparations. These results suggest that the membrane depolarization may be involved in the stimulating effects sodium nitroprusside in the guinea-pig vas deferens.     

Possible role of sildenafil in inhibiting rat vas deferens contractions by influencing the purinergic system

AIM: To evaluate the effect of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-selective type 5 phosphodiesterase, on isolated rat vas deferens and its connections with the purinergic system. METHODS: Epididymal and prostatic portions of isolated vas deferens were placed in organ baths containing Krebs' solution. Contractions were induced by noradrenaline (NA), adenosine triphosphate (ATP), alpha,beta-methylene ATP and electrical field stimulation (EFS). The effect of sildenafil on the contractions was compared with suramin and Evans blue (EB). RESULTS: NA, ATP, alpha,beta-methylene ATP and EFS caused contractions in both portions of vas deferens. NA-induced contractions were unaffected by sildenafil and suramin but potentiated by EB. ATP-induced contractions were non-competitively inhibited in both portions by sildenafil and suramin but potentiated by EB. alpha,beta-methylene ATP-induced contractions were unaffected by sildenafil but were inhibited in both portions by suramin and EB. EFS-induced contractions were inhibited by sildenafil and suramin while potentiated by EB. CONCLUSION: Sildenafil inhibited the contractions in both portions of vas deferens, as did suramin. We have suggested that purinergic system has a role in this antagonism and it seems to be mediated by an ATP-dependent mechanism instead of a receptor interaction.     

Long-term use of sertraline leads to alterations in contractility of rat isolated vas deferens

Previous experiments with rat isolated vas deferens have shown that sertraline pretreatment inhibits contractile responses to noradrenaline, KCl, serotonin and electrical field stimulation. In the present study, the aim was to investigate the effects of long-term use of sertraline on contractile responses of rat isolated vas deferens. Fifteen Sprague-Dawley rats were given long-term (21 days) sertraline treatment, while another 15 were used as control. Both vas deferens were excised. Epididymal and prostatic segments of each underwent electrical field and chemical stimulation (noradrenaline, serotonin, acetylcholine, adenosine-triphosphate). Epididymal and prostatic segments had different contraction characteristics. Long-term sertraline treatment inhibited contractile responses of vas deferens segments to electrical field stimulation. The responses to noradrenaline were amplified with a left shift on both segments. Responses to serotonin had only a left shift on epididymal segments, while no contractile responses were observed on prostatic segments of the groups. Long-term treatment with sertraline had peripheral effects on rat vas deferens contractility, and some of the effects may be through mechanisms other than the inhibition of serotonin re-uptake.     

Differences in the physiological response and ultrastructure of human and guinea pig vas deferens. Effects of prostaglandins, irradiation, and temperature

Marked differences were observed in the mechanical reactions of human and guinea pig vas deferens to prostaglandins, irradiation, and cooling. In human preparations prostaglandin E1 (0.1-1 ng/ml) had an augmentory effect on the contractile response after electrical neurostimulation (10 Hz, 0.3 ms, 3 s), but no visible influence (at concentrations ranging from 1 ng to 10 micrograms/ml) on the contractile response after electrical muscle stimulation (10 Hz, 40 ms, 3 s). In contrast, in guinea pig preparations (PGE1 (0.1-1 ng/ml) had an inhibitory effect on the contractile response after electrical neurostimulation and an augmentory effect (0.1-1 micrograms/ml) on the contractile response after electrical muscular stimulation. Human vas deferens showed higher radiosensitivity than guinea pig preparations. The neurotransmitters acetylcholine and catecholamines increased the radiosensitivity of guinea pig preparations, but not of human ones. Vas deferens reacted to short-time (15-120 s) cooling with an immediate temporary contraction, at 25 degrees C of short (seconds), at 5 degrees C of long (minutes) duration; after rewarming (5-37 degrees C) a second contraction appeared in guinea pig preparations, but not in human ones. Whereas the contraction to electrical neurostimulation (10 Hz, 0.3 ms, 3 s) was abolished in human preparations by cooling, it was only inhibited in guinea pig vas deferens. Electron microscopy showed differences in the ultrastructure of human and guinea pig vas deferens. Muscle cells were more widely separated in human vas deferens (generally 400 nm or more) than in guinea pig (approximately 100-200 nm), and the intracellular space in human preparations contained more collagen. The axons in human preparations contained predominantly large granular and agranular vesicles, those in guinea pig preparations small granular and agranular vesicles. The possible correlation between the physiological response of human and guinea pig vas deferens and the ultrastructural differences is discussed. The results indicate the possibility that other pharmacophysiological and toxicological phenomena could be essentially different in human and guinea pig material.     

Comparative effects of T‐type and L‐type Ca2+‐antagonists against noradrenaline‐induced contractions of human vas deferens

OBJECTIVE

To investigate the effects of the relatively selective T‐type Ca²⁺‐antagonists, mibefradil and flunarizine, and the L‐type Ca²⁺‐antagonist, nifedipine, on the contractions of longitudinal and circular muscles of human vas deferens, to elucidate the possible involvement of T‐type voltage‐gated Ca²⁺ channels (VOCs) in the contractile function of the tissue.

MATERIALS AND METHODS

Human vas deferens specimens from elective vasectomies were cut into strips of longitudinal muscle or transversely into rings of circular muscle. These were set up for tension recording and superfused with Krebs’ medium (36° C). Contractions were evoked by noradrenaline or high [K⁺]_o (in the presence of the L‐type Ca²⁺ agonist, FPL 64176) and the effects of Ca²⁺ antagonists were determined.

RESULTS

Noradrenaline (0.1–100 µmol/L) evoked rhythmic and tonic contractions of longitudinal and circular muscles, which were potently inhibited by nifedipine (≤0.1 µmol/L). Mibefradil (1–10 µmol/L) inhibited the contractions but was comparatively more effective in longitudinal than circular muscle. Flunarizine was ineffective except against contractions to low concentrations of noradrenaline. The drugs’ potencies as antagonists of L‐type VOCs were determined against contractions to high K⁺ (120 mmol/L in the presence of FPL 64176, 1 µmol/L). The contractions in longitudinal and circular muscle had different times to peak and decline but were inhibited comparably by nifedipine (50% inhibitory concentration, IC₅₀, longitudinal and circular muscle, ≈2 nmol/L) or by mibefradil (IC₅₀ longitudinal muscle, 1.1 µmol/L; circular muscle, 2.4 µmol/L) and were less sensitive to flunarizine (up to 30 µmol/L).

CONCLUSION

These results indicate that noradrenaline‐induced contractions of human vas deferens depend primarily on nifedipine‐sensitive L‐type VOCs, as opposed to mibefradil/flunarizine‐sensitive T‐type VOCs. The effects of mibefradil and flunarizine, at concentrations found to be effective against noradrenaline‐induced contractions, involve the blockade of L‐type VOCs. The modest differential effect of mibefradil in longitudinal and circular muscle is discussed in relation to factors that modulate activation and drug‐sensitivity of L‐type VOCs.     

Hormonal influence on the neurogenic response of the hamster vas deferens

The effect of castration on in vitro contractility of smooth muscle of the vas deferens and body of the bladder has been studied in the hamster. Castration produced supersensitivity to in vitro electrical stimulation and norepinephrine in the vas deferens, but had no effect on the body of the bladder. Castration also increased the maximum contractile response of the vas deferens to electrical stimulation, norepinephrine, ATP, acetylcholine and histamine. The changes in contractility of smooth muscle of the vas deferens developed slowly and may be explained by specific effects upon adrenergic and purinergic neurotransmission and/or non-specific effects upon smooth muscle cell membranes.     

The evaluation of sympathetic system-related contractile activity of the rat vas deferens after ligation and intra-abdominal placement of the testis.

OBJECTIVE: To evaluate the contractile response of the vas deferens in a model of stress, to determine any changes in sympathetic activity as a result of stress in the ipsilateral testis, which decreases blood flow to the contralateral testis. MATERIALS AND METHODS: The study comprised two groups of six rats each; group 1 underwent a sham operation, and in group 2 the right testis was placed into the abdominal cavity and the vas deferens ligated. After 30 days, the vasa deferentia were resected bilaterally and their isometric contractions recorded. Electrical-field stimulation (EFS) was applied through a pair of platinum electrodes and concentration-response curves constructed for noradrenaline at 37 degrees C and to a solution containing 80 mmol/L K+. RESULTS: The vasa deferentia in both groups showed similar contractile responses to EFS, which were frequency-dependent and maximal at 80 Hz. Noradrenaline-induced contractile activity was lower in amplitude in the vasa deferentia of group 2 than in the contralateral and ipsilateral vasa deferentia of group 1, which were not significantly different from each other. All groups responded similarly to high K+. CONCLUSION: Intra-abdominal placement of the testes with vas deferens ligation decreased the contractile response to noradrenaline in the ipsilateral vas deferens without altering the contractile response to EFS and high K+. This difference could be caused by a reduction in the number of postjunctional alpha-adrenergic receptors or decreased receptor sensitivity. Both possibilities suggest that the vas deferens may initiate sympathetic activity, which may be responsible for contralateral testicular deterioration.     

Effects of mexiletine on electrical field stimulation-induced contractile responses in the ipsilateral and contralateral vasa deferentia after unilateral testicular torsion/detorsion

AIM: To investigate testicular torsion-induced changes on the electrical field stimulation (EFS)-induced contractions in rabbit vasa deferentia and to evaluate the effect of mexiletine. METHODS: 18 male New Zealand albino rabbits were used in this experiment. Rabbits were divided into three groups: (1) control group (n = 6); (2) torsion group (n = 6), and (3) mexiletine group (n = 6). In the control group, vasa deferentia on both sides were harvested. In the torsion and mexiletine groups, the left testes of the rabbits were subjected to 720 degrees of clockwise torsion for 2 h and then detorsion was performed. In the mexiletine group, 50 mg/kg i.p. mexiletine was administered 1 h before detorsion. Following 24 h of the torsion, vasa deferentia on both sides were harvested and 2-cm strips including both the prostatic and epididymal portions were prepared to record EFS-induced contractions. RESULTS: Testicular torsion caused a significant inhibition in both phases of EFS-induced biphasic contractions of the ipsi- and contralateral vasa deferentia. Mexiletine treatment did not affect these inhibitory responses. Torsion/detorsion of the spermatic cord did not alter exogenously applied noradrenaline-induced contractions in both vasa deferentia. However, KCl-induced contractions diminished significantly in ipsilateral vas deferens of the torsion group and mexiletine restored this inhibition. CONCLUSIONS: Unilateral testicular torsion/detorsion leads to inhibition in both phases of EFS-induced biphasic contractions of the ipsi- and contralateral vasa deferentia by causing a defect in presynaptic nerve transmission. However, mexiletine has no effect on this inhibition. Inhibition of the KCl-induced contractions in the ipsilateral vas deferens, which indicates postsynaptic tissue damage, is restored by administering mexiletine 1 h prior to detorsion.     

Contraction of smooth muscle in Ca-free solution

The tonic contractions which are extremely resistant to removal of the external Ca were investigated in the rat vas deferens and myometrium. Both the noradrenaline response in the vas deferens and the oxytocin response in the myometrium could be repeatedly produced without appreciable diminution in Ca-free solution for more than 24 hrs. On the other hand, the tissue Ca content decreased exponentially after Ca-removal with a half time of 130-180 min. When Ca was readmitted, no indication of the early transient contraction was observed in the subsequent response in Ca-free solution, but the response was reduced compared with the response before Ca readmission. Verapamil suppressed the response in the presence of Ca, while it had very weak inhibitory effect even at 10 microM. Calmodulin antagonists of phenothiazine derivatives had a strong inhibitory effect on Ca-induced contractions, whereas they had very weak effects on the receptor-mediated contraction in Ca-free solution. Another calmodulin antagonist, W-7 suppressed both Ca-induced contraction and the contractions independent of external Ca. HA-1004, a vasodilator which has a structure similar to W-7, reduced the receptor-mediated contraction in Ca-free solution without much effect on Ca-induced contractions. These results may suggest that the receptor-mediated contractions resistant to Ca-removal are caused by some process without a contribution of the Ca-calmodulin system.     

Contraction independent of extracellular Ca by sodium vanadate in guinea-pig vas deferens

The effects of Ca removal and Ca antagonists on sodium vanadate-induced contractions of the guinea-pig vas deferens were studied. Sodium vanadate-induced tension development could be observed even 120 minutes after the removal of Ca, whereas K-contracture disappeared within 20 minutes. Spontaneous contractions induced by sodium vanadate were abolished by the removal of Ca. Verapamil and nifedipine did not show any effect on sodium vanadate-induced contraction, contrastingly, they blocked spontaneous contractions initiated by sodium vanadate. The effects of sodium vanadate on Ca contracture of depolarized preparations were also studied. Though the drug potentiated phasic contraction, it did not potentiate tonic component of Ca contracture. It was demonstrated that sodium vanadate induced tension development independently of extracellular Ca, presumably by releasing intracellularly bound Ca.     

Repeated vas occlusion and non-invasive reversal with styrene maleic anhydride for male contraception in langur monkeys

The feasibility of a spacing method for contraception, using Styrene Maleic Anhydride (SMA) as a vas occlusive agent, has been assessed in male langur monkeys. The vas deferens of 6 animals were occluded with 60 mg SMA in 120 microL DMSO. After 150 days, the occlusion was reversed by a technique which involved palpation, percutaneous electrical stimulation, forced vibratory movement, suprapubic percussion and per-rectal digital massage of the vas segments. The vas deferens were then re-occluded with SMA and reversed by the non-invasive method after three consecutive azoospermic samples. The second vas occlusion resulted in uniform azoospermia after the third ejaculation and reversal caused the reappearance of spermatozoa in the semen to severe oligozoospermic levels in the first two ejaculations and rising to normospermia in the subsequent ejaculations. Ultrastructure of the spermatozoa by SEM and TEM and sperm function tests revealed that the spermatozoa had recovered normal morphology. Vas morphology also regained a normal pseudostratified columnar epithelium containing basal and principal cells. The results suggest that the SMA-based spacing technique for male contraception could be extrapolated to the human by use of no-scalpel injection and non-invasive reversal.     

Effect of histamine on human vas deferens in vitro

Histamine, 2-methylhistamine and 4-methylhistamine produced concentration-related contractions in some isolated human vas deferens preparations. The contractions produced by histamine and its analogues were reversibly and competitively antagonised by the H1-receptor blocker, mepyramine, but not the H2-receptor blockers, burimamide and cimetidine. Phentolamine, atropine and guanethidine did not affect the excitatory action of histamine. Histamine and 4-methylhistamine did not show any inhibitory effect on KCl-induced tone. The results showed that histamine receptors were present in the human vas deferens and the histamine receptors mediating the excitatory response were likely to be H1-receptors.     

Regulation of rat caput epididymidis contractility by prostaglandins

Mechanical activity of the rat caput epididymidis in vitro was recorded using a videomicrography system. The effects of prostaglandin (PG)F2 alpha, PGE2, and aspirin on caput epididymidis contractility were determined by measuring the frequency of contraction, luminal diameter, and amplitude of contraction at various concentrations of each test compound in vitro. PGF2 alpha stimulated contractility of the tubules at physiological concentrations, while PGE2 reduced contractility. Aspirin strongly inhibited contractility at concentrations of 10(-3) and 10(-2)M. Endogenous levels of PGF2 alpha and PGE were determined for rat testes, caput, corpus, and cauda epididymidis and vas deferens. While the concentrations of PGE were consistently higher than those of PGF2 alpha, both compounds were relatively low in the testes, high in the vas deferens, and intermediate throughout the epididymis. Results from these experiments strongly suggest that PGs are important regulators of proximal epididymidis contractions and thus may regulate sperm transport through that organ.     

Effect of AVP on brain edema following traumatic brain injury

Objective: To evaluate plasma arginine vasopressin (AVP) level in patients with traumatic brain injury and investigate the role of AVP in the process of brain edema. Methods: A total of 30 patients with traumatic brain injury were involved in our study. They were divided into two groups by Glasgow Coma Scale: severe traumatic brain injury group (STBI, GCS≤8) and moderate traumatic brain injury group ( MTBI, GCS >8). Samples of venous blood were collected in the morning at rest from 15 healthy volunteers (control group) and within 24 h after traumatic brain injury from these patients for AVP determinations by radioimmunoassay. The severity and duration of the brain edema were estimated by head CT scan. Results: plasma AVP levels (ng/L) were (mean±SD): control, 3. 06±1. 49; MTBI, 38. 12±7. 25; and STBI, 66. 61±17. 10. The plasma level of AVP was significantly increased within 24 h after traumatic brain injury and followed by the reduction of GCS, suggesting the deterioration of cerebral injury (P<0. 01). And the AVP level was correlated with the severity (STBI r =0.919, P < 0.01; MTBI r = 0.724, P < 0.01) and the duration of brain edema (STBI r = 0. 790, P < 0. 01; MTBI r = 0. 712, P<0.01). Conclusions: The plasma AVP level is closely associated with the severity of traumatic brain injury. AVP may play an important role in pathogenesis of brain edema after traumatic brain injury.     

Local anaesthetics inhibit cholinergic and non-cholinergic neural and muscular contractions in avian tracheal smooth muscle

The effects of five different local anaesthetics: lignocaine, prilocaine, etidocaine, mepivacaine, bupivacaine, on tone, contractility, and on cholinergic and non-cholinergic responses of chick tracheal smooth muscle were studied and compared in vitro. The cholinergic and non-cholinergic contractions of the tracheal smooth muscle were elicited by electrical field stimulation, at a maximal voltage with 0.2 Hz and 0.2 ms square pulse duration, in the presence of adrenergic blockers, guanethidine, propranolol, and other drugs, e.g. indomethacin. Atropine was used to reduce the cholinergic responses due to electrical field stimulation and to applied acetylcholine (ACh). Lignocaine, in low concentrations, reduced these responses and also those produced by electrical field stimulation in the presence of atropine. In high concentration (greater than 100 times clinical concentrations), lignocaine abolished all the responses and produced a sustained contracture in the muscle. Among the local anaesthetics studied, bupivacaine and lignocaine were found to be more effective than mepivacaine, prilocaine and etidocaine, in reducing the cholinergic contractions produced by electrical field stimulation and by exogenous ACh. It was suggested that lignocaine, and other local anaesthetic drugs, may have an anti-spasmic effect on the tracheal smooth muscle, in that they inhibited the contractions induced by electrical field stimulation and by depolarizing agents.