C. Galeano

Effect of enkephalin on the micturition cycle of the cat.

The effect of the synthetic opiate [D-Ala2, Me-Phe4]-leu-enkephalin ( DAMLE ) on the micturition cycle of the cat was studied. In vivo assays were performed with young male cats under two different conditions: 1) decerebrated cats (D-cats), with an intercollicular transection of the brainstem, and 2) spinal cats (S-cats), with a spinal transection between C5-C6. In vitro studies were carried out on bladder strips taken from adult male cats. The D-cats showed two types of voiding patterns: the first type (I) was characterized by a smooth wave of pressure and an incomplete emptying of the bladder; the second type (II) began like the type I, but ended with a series of small contractions accompanied by small jets of liquid, resulting in the complete emptying of the bladder. DAMLE inhibited vesical contractions and completely inhibited voiding in D-cats at doses equal or superior to 250 micrograms/kg i.v.; no effect was noted with lower doses. Vesical contractions were hardly affected in S-cats, even at high doses (greater than 350 micrograms/kg i.v.). DAMLE did not affect electrically induced contractions of isolated bladder strips. Naloxone not only antagonized the inhibitory effects of DAMLE , but also induced per se a contraction of the bladder. These results indicate that enkephalinergic neurons are involved in the central neural circuitry of the micturition cycle in the cat, with an inhibitory effect at the level of either the ascending spinal pathways or the pontine Barrington s center.

Response of Urethral Smooth Muscles to Pharmacological Agents. II. Noncholinergic, Nonadrenergic Agonists and Antagonists

We studied the effects of a variety of noncholinergic, nonadrenergic agents on the smooth muscles of the cat urethra. Prostaglandin F2 alpha contracted both urethral muscle layers to a similar extent. Prostaglandin E2 contracted the longitudinal and relaxed the circular muscle layers. The effects of the prostaglandins seem to be directly myogenic since cholinergic and adrenergic blockers and tetrodotoxin did not affect them. Bradykinin and substance P contracted both urethral muscle layers. Other tested agonists (neurotensin, vasoactive intestinal peptide, cyclic 3,5 adenosine monophosphate, adenosine diphosphate sodium, cyclic 3,5 guanosine monophosphate sodium, bombesin) had no effect on the cat urethral smooth muscles.

Acupuncture analgesia in rabbits

&NA; The aim of this study was to verify the validity and reliability of analgesia elicited by acupuncture stimulation in rabbits. Ninety‐five experiments were performed using 21 adult animals. The reaction time of the avoidance response elicited by noxious heat stimulation on the snout, and the presence or absence of the start response elicited by pin‐prick and clamping of the skin were studied. Bilateral electric acupuncture stimulation in the area of Tsu‐san‐li and Shang‐chu‐hsu points in the hind legs was used. The animals were either held in a soft bag, loosely attached by cords, or suspended in a hammock; the eyes were either free of blindfolded. On the basis of operational behavioral measurements, it was found that acupuncture stimulation did not produced analgesia in undisturbed, placid animals. However, during agitated or fighting periods and the immobility reflex‐like state, sometimes associated with acupuncture maneuvers, long reaction times were observed. Pin‐princking and clamping stimulation of the skin were not reliable methods of noxious stimulation in the rabbit.

Has acupuncture an analgesic effect in the rabbit

&NA; We studied the effect of acupuncture stimulation on pain tolerance in rabbits. Painful stimulation was provided by a tungsten lamp focused on the snout. Four acupuncture points were selected: preocular, retroauricular, in the forepaw between the median and ulnar nerves and in the ears. A control series without acupuncture stimulation was also studied. Electrical stimulation was applied bilaterally through the acupuncture needles. A statistical analysis of the reaction time to the noxious stimulus demonstrated that the responses of the acupunctured animals were not significantly different from those of the controls. On the basis of operational behavioral measurements we conclude that the acupuncture procedure — as we did it — did not produce significant changes of pain tolerance in rabbits.

Vesicourethral motility following acute spinal cord transection in the cat.

The cause of urinary retention during the phase of spinal shock is still uncertain. In the cat with intact spinal cord, reflex voiding shows a coordination between the longitudinal and circular urethral muscles, the detrusor and the periurethral striated muscles. After transection of the spinal cord in cervical and/or thoracic segments, 26 of 28 cats failed to void. An incoordination between longitudinal, circular, detrusor and periurethral striated muscles was noticed simulating a urethro-urethral and urethrovesical dyssynergia. The 2 cats that voided 6 hours after the cord section showed a return of synergism between longitudinal, circular, detrusor and periurethral striated muscles. The conventional pharmacologic manipulation used during the early period following spinal cord transection, bethanechol chloride and phentolamine, failed to achieve proper bladder emptying because it did not correct the dyssynergic pattern.

New approach to study of voiding cycle in cat preliminary report on pharmacologic studies

The effect of autonomic active agents were studied on 23 anesthetized cats. The parameters recorded were circular and longitudinal urethral muscles, and bladder muscle contractions and relaxation as well as intravesical pressure during voiding cycles. Cholinergic stimulant (bethanechol) and blockage (atropine) excited or inhibited the bladder muscle and minimally affected the urethra. Alpha-adrenergic stimulant (norepinephrine) in nonatropinized animals produced mild stimulation on the bladder, and longitudinal-circular urethral muscle synergia appeared to be inadequate. In atropinized animals norepinephrine produced the reverse effect, causing marked inhibition. Alpha blockade (phentolamine) disinhibited the receptors mainly in the bladder and improved the urethral synergia. Beta stimulant (isoproterenol) inhibited the bladder and urethral muscles, and beta blockade (propranolol) stimulated the bladder and urethral muscles.

Bladder and Urethral Dynamics in Multiple Sclerosis-Like Animal Model

Multiple sclerosis-like disease was induced in 18 rabbits by immunization with guinea pig spinal cord. The urodynamic studies conducted in the immunized rabbits showed a significantly lower maximal urethral pressure and a lower bladder capacity than those in the control group. We compared the urodynamic, clinical and histopathological parameters in the immunized rabbits. We conclude that the rabbit is an acceptable model for studying the bladder and urethral dynamics during various phases of experimental allergic encephalomyelitis (multiple sclerosis-like disease).

Experimental allergic encephalomyelitis: a neurourological study.

To assess the neurourological disturbances produced by the perivascular inflammatory process in the acute phase of experimental allergic encephalomyelitis, we carried out a controlled study. Forty-six New Zealand male rabbits were inoculated with an encephalitogenic preparation. Twenty-seven of them developed neurological deficits in an average of 9.3 days postinoculation. A sample of 19 subjects was used as a control. The subjects were studied within 2 days after the manifestation of the first sign of encephalomyelitis. An average of eight successive cystosphincterograms were recorded. Their entire central nervous system was removed intact and suspended in 10% neutral buffered Formalin solution for 2 weeks, then cut into segments, embedded in paraffin, and finally stained with hematoxylin-eosin and Luxol Fast Blue. The results demonstrated a significant reduction of mean vesical capacity, maximum urethral pressure, and mean urethral pressure in the group with encephalomyelitis. Furthermore, we found a significant negative correlation between the average number of cellular perivascular infiltrates in the spinal sacral segment and urethral pressures. The results showed a significant negative correlation between supreamesencephalic inflammation and mean vesical capacity.