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PubMed1985

The determination of presynaptic KA values of methacholine and pilocarpine and of a presynaptic receptor reserve in the rat perfused heart.

Rat isolated perfused hearts with the right sympathetic nerves attached were loaded with [3H]-noradrenaline. The nerves were stimulated with up to 11 trains of 10 pulses at 0.1 Hz. The evoked increases of [3H]-noradrenaline overflow into the perfusate were measured in the presence of cocaine, corticosterone and propranolol. Activation of presynaptic muscarinic receptors by methacholine or pilocarpine inhibited the evoked transmitter release in a reversible and concentration-dependent manner. Preperfusion with phenoxybenzamine (5 microM) for 15 min (followed by a washout of 35 min) changed neither resting nor evoked overflow of [3H]-noradrenaline. The concentration-response curve of methacholine was shifted to the right after exposure of the hearts to phenoxybenzamine (1 microM) without depression of the maximum effect. Pretreatment with phenoxybenzamine (5 microM) reduced the maximum inhibition of release by about 50%. Analysis of the data gave a dissociation constant for the agonist-receptor complex (KA) of 4.0 microM and a receptor reserve of roughly 70%. Half-maximal inhibition of [3H]-noradrenaline release occurred when about 2% of the total receptor population was occupied. Comparison of the concentration-response data for methacholine and pilocarpine revealed a relative efficacy (methacholine/pilocarpine) of 16, a KA of 10 microM for pilocarpine and no receptor reserve for this agonist. The results show that KA values for methacholine and pilocarpine obtained at presynaptic receptors are similar to those obtained at postsynaptic muscarinic receptors. This is in agreement with the idea that muscarinic receptors located on postganglionic adrenergic nerves are not different from those located on effector sites of non-neuronal tissue.

Animals↗
PubMed1988

Reduced cyclic myopia with pilocarpine gel.

Pilocarpine 4% gel and pilocarpine 4% solution were compared in young normal subjects for their effects on induced myopia. The pilocarpine 4% solution produced marked myopia lasting one to two hours which indicates that a qid therapeutic regimen produces about three to six hours of blurred vision during waking hours. The gel-induced myopic effects returned to normal in most subjects nine hours after a single instillation. Thus, pilocarpine-gel-induced myopic effects occur principally while asleep and are reduced substantially upon awakening. This allows patients to carry on normal activities throughout the day.

Adult↗
PubMed1977

Intraocular pressure control with twice-daily pilocarpine in two vehicle solutions.

In a double-blind study no significant difference was found in intraocular pressure control, mean pressure or comparative binocular intraocular pressure difference between pilocarpine in Adsorbobase compared to pilocarpine in 0.5% hydroxypropl-methylcellulose solution. Intraocular pressure control was achieved on fewer than 60% of visits using pilocarpine twice daily in either of the 2 vehicles. While pilocarpine retained some residual hypotensive effect 12 hours after application, twice-daily dosage with the solutions tested gave inadequate control for clinical usefulness.

Adult↗
PubMed1979

[Studies on the psychological profile of glaucoma patients and on the action of the long-term pilocarpine vehicle Ocusert (author's transl)].

The investigations were carried out on two groups of newly diagnosed glaucoma patients. Each group contained 25 patients. One group received standard pilocarpine drops, the other the Ocusert pilocarpine system. Ocusert is a system which releases a constant amount of pilocarpine over a period of seven days. The psychological profile of the patients was investigated with the aid of the Freiburg inventory test sheet and the Giessen test. Glaucoma patients appear to have a particular personality structure. After three months' Ocusert treatment psychological tests showed a decrease in nervousness, irritability and emotional instability in all patients. In the group given pilocarpine drops the above parameters were intensified. The results of Ocusert treatment are in agreement with those obtained by other authors. In addition, there was considerably less miosis and myopia than during trop treatment. Even though the patients had initial difficulties with Ocusert, they learnt how to handle it correctly within one to seven days.

Adolescent↗
PubMed1979

A clinical trial with Piloplex--a new long-acting pilocarpine compound: preliminary report.

A clinical comparison of the effect of Piloplex (an emulsion containing a new pilocarpine polymer compound) to that of pilocarpine hydrochloride 2% q.i.d.hloride on the intraocular pressure (IOP) was performed on 93 eyes of 51 open-angle glaucoma cases. Clinical studies showed that Piloplex produced a prolonged therapeutic effect, this being consistent with the slow release pattern it has displayed during in vitro experiments. Comparison of diurnal IOP measurements of 84 eyes have shown that when treated with Piloplex, 11 b.i.d., 58 eyes (69%) were under control (IOP values less than 20 mm Hg), whereas only 34 of these 84 eyes (40.5%) were under control when treated with pilocarpine hydrochloride 2% q.i.d. The overall mean diurnal IOP value of the 84 eyes during the treatment with Piloplex, 11 b.i.d., was lower by 2.89 mm Hg (P less than 0.005) than the overall mean diurnal IOP of the same eyes while treated with pilocarpine hydrochloride 2% q.i.d.

Adult↗
PubMed1980

[Experiences in a double-blind study with different concentrations of timolol and pilocarpine (author's transl)].

Fifty patients with chronic open-angle glaucoma were studied in a double-blind study with Timolol ophthalmic solution, in a concentration of 0.1%, 0.2% and 0.5%, and Pilocarpine eye drops 1%, 2% and 4% over a period of seventeen weeks. Timolol was instilled twice daily into the conjunctival sack, or Pilocarpine four times daily. The results of the investigations may be summarised as follows: Timolol (0.1%-0.5%) achieved a mode-rate reduction in I.O.P. of 29%, compared to a 10.3% drop with Pilocarpine (1%-4%). Under treatment with Timolol, there was a statistically significant reduction in pulse rate of 12%, also a slight drop in blood-pressure of 3.5% systolic and 2.5% diastolic. During this study, those treated with Timolol showed no statistical changes of visual acuity, visual field, or on slit lamp examination and ophthalmoscopy of the optic disk and retina. The average pupillary diameter and tear flow (Schirmer Test), were little changed in the group of patients treated with Timolol, whereas in the Pilocarpine group, the size of the pupil decreased by 30.5% as expected.

Adult↗
PubMed1980

Corneal metabolism of pilocarpine in pigmented rabbits.

Cornea, aqueous humor, and iris-ciliary body levels of pilocarpine and its metabolite pilocarpic acid were determined in mixed-breed rabbits following topical dosing with 25 microliters of 1 X 10(-2) M pilocarpine. From the time-drug concentration profile it is clear that extensive metabolism of pilocarpine occurs in the cornea of pigmented rabbits. This finding contrasts sharply with similar studies in albino rabbits where relatively low levels of pilocarpine acid were observed. It is estimated that the first-order metabolism rate constant in albino rabbits is approximately two orders of magnitude smaller than in pigmented animals. A significant observation from this finding is the possibility that the reported greater dose requirement for heavily pigmented individuals may not be due to drug-pigment binding alone but also to extensive corneal drug metabolism.

Animals↗
PubMed1996

Protective effects of GABAergic drugs and other anticonvulsants in lithium-pilocarpine-induced status epilepticus.

Administration of subconvulsive dose of pilocarpine (30 mg/kg s.c.) to rats pretreated with lithium chloride (3 meq/kg i.p.) produced a state of status epilepticus in animals. The animals showed characteristic symptoms of generalized convulsions, wet dog shakes (WDS), forelimb clonus and falling back. The symptoms of status epilepticus (SE) developed within 26.8 +/- 3.6 min after administering pilocarpine and these symptoms continued uninterrupted. The phenomenon was totally reproducible, with a consistent latency of onset of seizures and a high mortality rate. The symptoms were blocked by atropine, scopolamine and the GABAergic agents GABA, sodium valproate, (+)-baclofen and clonazepam when given prior to pilocarpine, but not when administered 30 min after pilocarpine administration.

Animals↗
PubMed1995

Evaluation of multiple doses of 4 and 6% timolol, and timolol combined with 2% pilocarpine in clinically normal beagles and beagles with glaucoma.

Topically applied 4% timolol, 4% timolol combined with 2% pilocarpine, 6% timolol, and 6% timolol combined with 2% pilocarpine were evaluated in clinically normal Beagles and Beagles with glaucoma. The drugs were instilled twice daily for 5 days. Changes in intraocular pressure (IOP), pupil size, and heart rate were recorded on days 1, 3, and 5 at 0, 2, 5, and 8 hours, starting at 8:30 AM. In clinically normal dogs, 4 and 6% topically administered timolol did not cause consistent reductions in IOP; however, with addition of 2% pilocarpine, IOP was consistently lower. In the Beagles with glaucoma, 4 and 6% timolol and, to a greater extent, 4 and 6% timolol combined with 2% pilocarpine lowered IOP. The combinations lowered IOP and reduced pupil size consistently. In all test groups, either 4 or 6% topically applied timolol caused approximately 10% decrease in mean heart rate.

Administration, Topical↗
PubMed1977

Pilocarpine stimulation of the bronchiolar Clara cell secretion.

Fasted rats were given a single cholinergic subcutaneous injection of pilocarpine and sacrificed from 30 minutes to 24 hours later. Secretory granules were extruded by Clara cells as early as 30 minutes after pilocarpine administration. Simultaneously and thereafter, Clara cells displayed dilated cisternae of endoplasmic reticulum and active assembly of secretory granules at the Golgi complex. After 1 to 2 hours, new secretory granules reached the cell surface and were discharged into the bronchiolar lumen by exocytosis. At 4 hours the Clara cell organelles appeared quiescent. Complete cell recovery apparently occurred by 12 to 24 hours after pilocarpine administration. The accelerated secretion by Clara cells with pilocarpine provides an evidence of their exocrine character and the exocytotic secretory mechanism. The morphologic data indicate that the production and secretion by Clara cells may be controlled by neurohumoral mechanism.

Animals↗
PubMed1997

Asymmetrical effects of the unilateral implant of pilocarpine on the preoptic-anterior hypothalamic area on spontaneous ovulation of the adult rat.

The effects on ovulation at the next estrus after unilaterally implanting pilocarpine in the preoptic-anterior hypothalamic area (POA-AHA) of rats on each day of the estrous cycle were analyzed. Implantation on the left side of POA-AHA on the day of estrus blocked ovulation in all animals, whereas implantation on the right side did not (0/5 vs. 4/4, P < 0.05). Implantation on diestrus 1 or 2 on either side of the POA-AHA blocked ovulation. Implantation on the right side of the POA-AHA at the day of proestrus blocked ovulation (1/6 animals ovulated), while 10/12 with pilocarpine on the left side ovulated (P < 0.05). The administration of 3.7 micrograms of GnRH at 13:00 h on the expected day of proestrus induced ovulation in 36/42 treated animals. In rats with a pilocarpine implant, the injection of estradiol benzoate on diestrus 2 restored ovulation only in those animals with the pilocarpine implant placed in the left side of the POA-AHA, performed on the day of estrus. The results support the previous statements that in the adult rat POA-AHA, the cholinergic mechanism regulating preovulatory GnRH release, is lateralized. In addition, at the beginning of the estrous phase, the POA-AHA-cholinergic system needs to remain undisturbed for normal ovulation to take place at the next estrus.

Animals↗
PubMed1997

Effectiveness of vigabatrin against focally evoked pilocarpine-induced seizures and concomitant changes in extracellular hippocampal and cerebellar glutamate, gamma-aminobutyric acid and dopamine levels, a microdialysis-electrocorticography study in freely moving rats.

Limbic seizures were evoked in freely moving rats by intrahippocampal administration of the muscarinic agonist pilocarpine via the microdialysis probe (10 mM for 40 min at 2 microl/min). This study monitored changes in extracellular hippocampal gamma-aminobutyric acid (GABA), glutamate and dopamine levels after systemic (30 mg/kg/day) or local (intrahippocampal or intranigral, 5 mM or 600 microM for 180 min at 2 microl/min) vigabatrin administration, and evaluated the effectiveness of this antiepileptic drug against pilocarpine-induced seizure activity. Extracellular GABA and glutamate overflow in the ipsilateral cerebellum was studied simultaneously. Microdialysis was used as an in vivo sampling technique and as a drug-delivery tool. Electrophysiological evidence for the presence or absence of seizures was recorded with electrocorticography. The observed alterations in extracellular hippocampal amino acid levels support the hypothesis that muscarinic receptor stimulation by the intrahippocampal administration of 10 mM pilocarpine is responsible for the seizure onset, and that the amino acids maintain the sustained seizure activity. The focally evoked pilocarpine-induced seizures were completely prevented by intraperitoneal vigabatrin premedication for 7 days or by a single intraperitoneal injection. Effective protection was reflected in a lack of sustained elevations of hippocampal glutamate levels. Rats receiving vigabatrin intrahippocampally or intranigrally still developed seizures, although there appeared to be a partial protective effect. During the intrahippocampal perfusion with 5 mM vigabatrin, extracellular hippocampal GABA levels increased, whereas the extracellular glutamate and dopamine overflow decreased. The lack of a complete neuroprotection after local vigabatrin treatment is discussed.

Animals↗
PubMed1976

Effect of pilocarpine ocular therapeutic systems on diurnal control of intraocular pressure.

The pilocarpine ocular therapeutic system is an innovative ocular drug delivery system which releases pilocarpine into the tear film at a constant rate of 20mug/hr or 40mug/hr. The system was evaluated in 22 hospitalized patients with bilateral open angle glaucoma to determine its ability to control ocular pressure throughout the diurnal interval. Only the right eye of each patient was treated with the pilocarpine ocular therapeutic system; the other eye served as a control. Twelve pressure measurements were made with a noncontacttorometer over a 34-hour test period. In general, the pilocarpine ocular therapeutic system provided satisfactory around-the-clock control of intraocular pressure and was well tolerated by the patients.

Adult↗
PubMed1998

Development of self-sustaining limbic status epilepticus by continuous ventral hippocampal stimulation followed by low dose pilocarpine in rats.

Sequential treatment of rats with low doses of lithium and pilocarpine, a high dose of pilocarpine, or continuous hippocampal stimulation [CHS] (9 epochs, 10 min each) is reported to result in status epilepticus (SE). We report a novel method to establish SE based on continuous ventral hippocampal stimulation (5 epochs) followed by low dose pilocarpine (40 mg/kg) challenge. Motor limbic seizures occured in all the control rats. The latency to spike activity was 15 +/- 1 min after pilocarpine administration. Ventral hippocampal [VHc] and cortical EEG recordings were used to monitor the protective effect of diazepam (5 mg/kg). Except phenobarbital, all the three drugs completely prevented all the phases of seizure activity. Initiation of spikes was significantly prolonged by phenobarbital pretreatment. Further study on the characteristics of these convulsions offers a unique possibility for the recognition of brain regions, pathways, and neurotransmitters engaged in the spread of seizures in this model.

Animals↗
PubMed1976

Pilocarpine hydrochloride in ophthalmic solutions: modification of a high-pressure liquid chromatographic determination and survey.

Pilocarpine undergoes 2 important reactions in solutions, epimerization to isopilocarpine and hydrolysis to pilocarpic acid. There is no official USP limit for isopilocarpine or pilocarpic acid in pilocarpine hydrochloride ophthalmic solutions. An existing high-pressure liquid chromatographic (HPLC) method was modified by changing the buffer system to permit its use with constant-pressure as well as constant-volume instruments. The procedure separates all 3 components on a cation exchange resin; pilocarpine and isopilocarpine are determined directly and pilocarpic acid indirectly. Ophthalmic solutions and drug substances were obtained from substantially all the United States marketers of pilocarpine opthalmic solutions and were analyzed by the modified HPLC method. Results of the survey show that isopilocarpine is present to the extent of 0.4-3% and pilocarpic acid at levels of 0.6-7% of total alkaloid.

Chemical Phenomena↗
PubMed1991

Magnetic resonance imaging of canine salivary glands after ductal ligation and stimulation by pilocarpine.

We performed magnetic resonance imaging in six dogs after submandibular ductal ligation on one side, followed by secretory stimulation with intraperitoneal injection of pilocarpine (5 mg/kg). On the images obtained after ductal ligation but before stimulation, there was no significant change in signal intensity on either side. After injection of pilocarpine the signal intensity of the ligated gland increased significantly (p less than 0.01) in T2-weighted images and nonsignificantly in inversion recovery images, and remained constant in T1-weighted images. Significant (p less than 0.01) volume increases of the glands after ligation and stimulation were measured for the T1, T2, and inversion recovery protocols. These findings likely reflect the retention of saliva caused by pilocarpine stimulation and the absence of drainage through the obstructed duct. The results indicate that the T2-weighted images obtained after pilocarpine stimulation may be useful for studying patients with disturbance of major salivary gland function and may provide an objective basis for the noninvasive diagnosis of unilateral stenosis.

Animals↗
PubMed2001

Feeding-related motor patterns of the locust suboesophageal ganglion induced by pilocarpine and IBMX.

The mandibular motor pattern induced by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) in isolated locust suboesophageal ganglia (SOG) was investigated and compared with the motor pattern induced by pilocarpine in an already established preparation of the SOG. Motor patterns occurring after bath application of IBMX or pilocarpine were recorded extracellularly from suitable nerves of isolated SOG. For a quantitative evaluation of long (15 min) sequences of rhythmic neural activity containing several hundred cycles, spectral analysis of spike trains was applied. Using a set of characteristic parameters extracted from spectra computed for each individual preparation, quantitative comparisons of the rhythms induced by IBMX and pilocarpine were made. Significant differences in regularity, frequency of oscillation, and intra-burst frequency were found whereas the phase relationships of different motor pools were similar. Differences in the effect of the drugs on the activity recorded extracellularly from mandibular closer motoneurones were investigated further using intracellular recordings. Our findings imply that the IBMX-induced motor pattern is a suitable in vitro model of mandibular central motor control like the pilocarpine induced pattern. The better regularity is an advantageous feature for further experiments on central pattern generation. Information on second messengers involved in central pattern generation provided by the pharmacological profile of IBMX forms a basis for pharmacological and histological investigations on the mandibular central pattern generating network.

Journal Article↗
PubMed1995

Rhythmic patterns in the thoracic nerve cord of the stick insect induced by pilocarpine

Bath application of the muscarinic agonist pilocarpine onto the deafferented stick insect thoracic nerve cord induced long-lasting rhythmic activity in leg motoneurones. Rhythmicity was induced at concentrations as low as 1x10(-4) mol l-1 pilocarpine. The most stable rhythms were reliably elicited at concentrations from 2x10(-3) mol l-1 to 5x10(-3) mol l-1. Rhythmicity could be completely abolished by application of atropine. The rhythm in antagonistic motoneurone pools of the three proximal leg joints, the subcoxal, the coxo-trochanteral (CT) and the femoro-tibial (FT), was strictly alternating. In the subcoxal motoneurones, the rhythm was characterised by the retractor burst duration being correlated with cycle period, whereas the protractor burst duration was almost independent of it. The cycle periods of the rhythms in the subcoxal and CT motoneurone pools were in a similar range for a given preparation. In contrast, the rhythm exhibited by motoneurones supplying the FT joint often had about half the duration. The pilocarpine-induced rhythm was generated independently in each hemiganglion. There was no strict intersegmental coupling, although the protractor motoneurone pools of the three thoracic ganglia tended to be active in phase. There was no stereotyped cycle-to-cycle coupling in the activities of the motoneurone pools of the subcoxal joint, the CT joint and the FT joint in an isolated mesothoracic ganglion. However, three distinct 'spontaneous, recurrent patterns' (SRPs) of motoneuronal activity were reliably generated. Within each pattern, there was strong coupling of the activity of the motoneurone pools. The SRPs resembled the motor output during step-phase transitions in walking: for example, the most often generated SRP (SRP1) was exclusively exhibited coincident with a burst of the fast depressor trochanteris motoneurone. During this burst, there was a switch from subcoxal protractor to retractor activity after a constant latency. The activity of the FT joint extensor motoneurones was strongly decreased during SRP1. SRP1 thus qualitatively resembled the motoneuronal activity during the transition from swing to stance of the middle legs in forward walking. Hence, we refer to SRPs as 'fictive step-phase transitions'. In intact, restrained animals, application of pilocarpine also induced alternating activity in antagonistic motoneurone pools supplying the proximal leg joints. However, there were marked differences from the deafferented preparation. For example, SRP1 was not generated in the latter situation. However, if the ipsilateral main leg nerve was cut, SRP1s reliably occurred. Our results on the rhythmicity in leg motoneurone pools of deafferented preparations demonstrate central coupling in the activity of the leg motoneurones that might be incorporated into the generation of locomotion in vivo.

Journal Article↗