Cholinergic muscarinic receptor blockade suppresses arginine- and exercise-induced growth hormone secretion in type I diabetic subjects

Stimulatory cholinergic pathways participate in the regulation of GH release, and cholinergic receptor antagonists inhibit GH secretion in normal man. Whether similar mechanisms are active in subjects with insulin-dependent diabetes is not known, yet this is of potential importance since GH hypersecretion has been implicated in both the acute and chronic complications of diabetes mellitus. To address this question we studied the effects of cholinergic receptor blockade on stimulated GH release in 18 type I diabetic men. Paired tests were performed using 1 of 2 different stimuli (30 g arginine, iv, or physical exercise for 30 min) with or without prior administration of the selective cholinergic muscarinic receptor antagonist pirenzepine (30 mg, iv). Arginine elicited a mean peak serum GH level of 9.0 +/- 1.9 (+/- SEM) micrograms/L, which was completely suppressed by pirenzepine (1.5 +/- 0.4 micrograms/L; n = 8; P less than 0.01). Blood glucose rose after arginine infusion and was not affected by pirenzepine. Serum GH levels rose during physical exercise to a mean peak of 7.3 +/- 1.6 micrograms/L, which was abolished by pirenzepine (1.2 +/- 0.3 micrograms/L; n = 10; P less than 0.01). Blood glucose was not influenced by pirenzepine. Two subjects had no serum GH response to exercise. We conclude that GH secretion in subjects with insulin-dependent diabetes, as in normal subjects, is modulated by cholinergic pathways and is responsive to pharmacological suppression by muscarinic receptor blockade. This may have implications for therapeutic trials designed to lower elevated GH levels in subjects with diabetes mellitus.

Effects of bromocriptine on sweat gland function during heat acclimatization

This study examined the involvement of the hormones aldosterone and prolactin in sweat gland function during heat acclimatization. Two groups of male subjects (n = 8) were tested - one receiving a placebo (control), the other receiving bromocriptine. Both groups performed cycle ergometer exercise at 50% of maximal oxygen uptake over 10 consecutive days in an environmental chamber maintained at 39 degrees C and 30% relative humidity. Duration of exercise was 90 min on days 2-4 and 6-9, and 45 min on test days 1, 5 and 10. Electrolyte concentrations were determined by total body washdown. Prolactin increased (p less than 0.001) during exercise on day 1 in the control group but not on days 5 and 10. In contrast, prolactin was suppressed by bromocriptine and did not rise in response to exercise or heat exposure. Plasma aldosterone increased during exercise in both groups, showing no differences between groups. The sodium concentration in sweat decreased significantly (p less than 0.05) in the control group from day 1 to 10 but was unchanged in the treatment group. These data suggest that acclimatization-related changes in sweat gland function may be attenuated by increases in central dopaminergic activity and implicate prolactin in control of sweat gland function.

Sweating patterns in humans: I. Exercise- and pilocarpine-induced forehead sweating in healthy individuals

In cluster headache, forehead sweating is frequently pathological and for this reason it is important to know the normal pattern. In the present work, sweating was induced by exercise and pilocarpine in 14 healthy individuals in the age group 24-50 years. A comparison was also made with patterns of heat-induced forehead sweating. No definite left-right asymmetry or medial-lateral preponderance were observed. As expected, the sweat patterns following body heating and exercise were rather similar. However, there was a significant relative increase in lateral forehead sweating with heat-induction as compared to pilocarpine-induction. In comparative intra- or inter-individual studies of forehead sweating, the method of sweat provocation may, therefore, not be indifferent.

Aspirin enhances evaporation in hydrated and dehydrated rats

The effect of acetysalicylic acid (aspirin) on thermoregulation in a warm environment was studied in hydrated and dehydrated adult rats to test the hypothesis that dehydration hyperthermia can be modified by an antipyretic drug. Metabolic rate (MR), evaporative water loss (EWL), and deep body temperature (Tb) were measured during 2 h of exposure to an ambient temperature of 36 degrees C after the rats had received an oral pellet of aspirin (100 mg.kg-1) or placebo. The dehydrated placebo group had a higher Tb and lower EWL than the hydrated placebo group. Aspirin increased MR and EWL in both hydrated and dehydrated animals. Aspirin did not affect Tb in hydrated rats, but reduced Tb by 0.2 degree C in dehydrated rats during the heat exposure. The elevation in EWL appears to be a thermoregulatory response to increased heat production in both hydrated and dehydrated animals after aspirin treatment. The possibility that aspirin may act in dehydrated animals to restore central thermosensitivity toward hydrated levels needs to be tested further.

Cutaneous manifestations of acrodynia (pink disease)

A 14-month-old girl who presented with multiple systemic complaints was found to have gingivitis, peeling of her palms and soles, and a peculiar acral eruption. A diagnosis of acrodynia, or pink disease, was confirmed by elevated levels of mercury in the urine. The many cutaneous manifestations of this once common disease are discussed.

Effect of VIP on sweat secretion and cAMP accumulation in isolated simian eccrine glands

Although vasoactive intestinal peptide (VIP)-immunoreactive nerves have been identified around the eccrine sweat glands, their functional significance is unknown. We found that VIP evokes eccrine sweat secretion in isolated monkey palm eccrine sweat glands in vitro as profusely as does isoproterenol (Iso), however, at concentrations two orders of magnitude lower than that of Iso. Like Iso sweating, the VIP sweating was relatively insensitive to removal of Ca2+ from the medium. The time course of adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in the secretory coil paralleled that of sweat secretion. However, unlike Iso stimulations, both VIP-induced cAMP level and VIP sweat rate markedly declined with time. The attenuation of VIP sweat rate was reversed by forskolin and by theophylline, suggesting that the attenuation is caused partially by desensitization of the receptor-cyclase complex and/or by cAMP breakdown by phosphodiesterase. Forskolin stimulated the VIP-induced cAMP level more than can be expected from a simple additive effect. The sudorific effects of a submaximal concentration of VIP (6 X 10(-9) M) and that of methacholine (MCh) (10(-8) M) were only additive. The VIP-induced cAMP level was markedly augmented by MCh and further enhanced by Iso with or without theophylline. Thus the most salient biochemical consequence of the VIP-ergic component of sweat gland innervation is to induce synergistic amplification of tissue cAMP accumulation. The functional significance of synergistically accumulated cAMP in physiological eccrine sweating remains to be studied.

Effects of topically-applied antiperspirant on sweat gland function

In subjects exposed to a hot environment, short-term topical pretreatment with aluminium zirconium tetrachlorhydrate delayed the onset of visible sweating although it failed to prevent the response. The delay was considered most probably to be due to the occlusive action, in the duct within the upper epidermis, of aluminium-containing conglomerates, which disappear after continuous sweating. However, microanalytical evidence indicated that ionic transport within the fundus secretory cells was also modified.

Effect of Bellergal Retard on climacteric complaints: a double-blind, placebo-controlled study

The effect of Bellergal Retard (BR) on climacteric complaints was evaluated versus a placebo in an 8-wk double-blind study, followed by a 4-wk open study in which only BR was used as medication. There was a marked decrease in complaints in both the BR and the placebo groups. Statistically significant differences were observed between the groups after 2 and 4 wk of treatment, indicating superior results with BR. After 8 wk of study however, these differences were no longer apparent. It was concluded that studies on medication for climacteric complaints should not only be placebo-controlled, but also be of at least 8 to 12 wk duration for proper evaluation.

Hyposecretion of beta-adrenergically induced sweating in cystic fibrosis heterozygotes

In order to determine if expression of the cystic fibrosis gene can be detected in heterozygotes, we determined sweat responses induced by local stimulation with cholinergic and beta-adrenergic agents for 20 heterozygotes, 19 age- and sex-matched controls, and five subjects with cystic fibrosis. Active sweat glands were counted and sweat droplets were collected in constant bore capillaries and measured optically. Each subject was tested two to six times. The central finding was that the sweat response of carriers was significantly lower than controls to beta-adrenergic stimulation (p = 0.0013, two-tailed t test; p less than 0.02, Mann-Whitney U), while cystic fibrosis homozygotes did not sweat at all. In contrast, the cholinergic sweat responses did not differ between carriers and controls. For both groups the correlation between cholinergic and beta-adrenergic sweating was positive, but a linear regression of beta-adrenergic sweat responses as a function of cholinergic sweat responses yielded slopes that were significantly different for the two groups. The ratio of beta-adrenergic to cholinergic sweating was plotted for each subject; the mean ratio of the carriers was approximately half of the mean for the controls (p = 0.0002 using t test or p less than 0.002 using the Mann-Whitney U). Our results confirm previous studies and provide new evidence that carriers have, on average, a beta-adrenergically stimulated secretory response that is significantly reduced relative to the control response.

Thermoregulation in hyperhydrated men during physical exercise

The influence of hyperhydration on thermoregulatory function was tested in 8 male volunteers. The subjects performed cycle exercise in the upright position at 52% Vo2max for 45 min in a thermoneutral (Ta = 23 degrees C) environment. The day after the control exercise the subjects were hyperhydrated with tap water (35 ml X kg-1 of body weight) and then performed the same physical exercise as before. Total body weight loss was lower after hyperhydration (329 +/- 85 g) than during the control exercise (442 +/- 132 g), p less than 0.05. The decrease in weight loss after hyperhydration was probably due to a decrease in dripped sweat (58 +/- 64 and 157 +/- 101 g, p less than 0.05). With hyperhydration delay in onset of sweating was reduced from 5.8 +/- 3.2 to 3.7 +/- 2.0 min (p less than 0.05), and rectal temperature increased less (0.80 +/- 0.20 and 0.60 +/- 0.10 degrees C, p less than 0.01). The efficiency of sweating was higher in hyperhydrated (81.4%) than in euhydrated subjects (57.1%), p less than 0.01. It is concluded that hyperhydration influences thermoregulatory function in exercising men by shortening the delay in onset of sweating and by decreasing the quantity of dripped sweat. As a result, the increases in body temperature in hyperhydrated exercising men are lower than in normally hydrated individuals.

Development and properties of the secretory response in rat sweat glands: relationship to the induction of cholinergic function in sweat gland innervation

Previous studies suggest that the sympathetic innervation of the sweat glands in the rat is initially noradrenergic and during development undergoes a transition in neurotransmitter phenotype to become cholinergic. To characterize this system and its development further, we have examined the adrenergic and cholinergic components of the secretory response in adult and immature rats and have studied the onset of sweating in the plantar sweat glands of developing rats. Stimulation of the sciatic nerve in adult rats elicited a secretory response which was completely blocked by the cholinergic antagonist, atropine, and was unaffected by adrenergic antagonists, indicating that nerve-evoked secretion was cholinergic. In adult rats, the sweat glands were quite sensitive to cholinergic agonists. In addition to acetylcholine, the mature sweat gland innervation contains vasoactive intestinal peptide (VIP). In some rats, the injection of VIP alone elicited a secretory response which was blocked by atropine, suggesting that the response to VIP was mediated cholinergically. In contrast to cholinergic agonists, the glands responded relatively infrequently and with reduced volumes of sweat to the alpha- and beta-adrenergic agonists 6-fluoronorepinephrine and isoproterenol. However, when VIP, which is a potent vasodilator, was simultaneously injected with adrenergic agonists, glands in many of the injected footpads exhibited a secretory response. The response to adrenergic agonists in combination with VIP was reduced by atropine and by phentolamine plus propranolol, but was blocked completely only by a combination of the three antagonists, indicating that both adrenergic and cholinergic mechanisms were involved. In immature rats, sweating evoked by nerve stimulation first appeared at 14 days of age in 25% of the rats tested. Both the percentage of rats sweating and the number of active glands increased rapidly. At 16 days, 50% of the rats tested exhibited some active glands, and by 21 days all rats tested exhibited a secretory response. In 16-day-old rats, nerve-evoked sweating was almost completely inhibited by local injection of 1 microM atropine, but was unaffected by phentolamine and propranolol in concentrations up to 10 microM. Similarly, the glands were sensitive to 10 microM muscarine, but they exhibited no secretory response to the alpha-adrenergic agonists, clonidine and 6-fluoronorepinephrine, nor to the beta-adrenergic agonist, isoproterenol, at concentrations up to 50 microM. The simultaneous injection of VIP with adrenergic agonists did not reveal an adrenergically mediated secretory response in 16-day-old animals.(ABSTRACT TRUNCATED AT 400 WORDS)

Generalized hypersensitivity reaction to intravesical thiotepa and doxorubicin

We describe an unusual case of pruritus after intravesical thiotepa, and diaphoresis, shortness of breath, chills and pruritus following intravesical doxorubicin therapy. Such generalized allergic reactions occur uncommonly after bladder instillation of thiotepa or doxorubicin.

Human thermoregulation after atropine and/or pralidoxime administration

The effects of intramuscular saline (control), atropine (2 mg), and/or pralidoxime (600 mg) on heat exchange was evaluated in four healthy males during seated, cycle exercise (55% Vo2 peak) in a temperate environment (Ta = 30.3 degrees C, Pw = 1.0 kPa). Esophageal (Tes), rectal (Tre), and mean skin temperatures (Tsk), and chest and forearm sweating (ms) were continuously measured. Skin blood flow (FBF) from the forearm was measured twice each minute by venous occlusion plethysmography. Whole body sweating was calculated from weight changes. The expected result of atropine injection, decreased eccrine sweating (-60%, p less than 0.05) and elevated esophageal (+0.4 degree C, p less than 0.05) and skin temperatures (+2.1 degrees C, p less than 0.05) was observed relative to control. Heart rate (+28 b X min-1) and FBF (+9 ml X 100 ml-1 X min-1) were higher after atropine. Pralidoxime, in general, did not affect the core and skin temperature responses to the exercise differently from control; however, a slightly elevated FBF (+3 ml X 100 cc-1 X min-1, 33%) compensated for the reduction in whole body sweating (-45%, p less than 0.05] that we observed. The combination of the drugs resulted in significantly higher esophageal (0.4 degree C) and skin (0.9 degree C) temperatures than atropine alone, as has been previously shown. The thermoregulatory disadvantage of inhibited sweating by atropine was partially compensated for by enhanced skin blood flow in this environment where Ta less than Tsk. Pralidoxime was shown to decrease whole body sweating, by a mechanism as yet unexplained.

Effect of beta-adrenoceptor blockade and calcium antagonism, alone and in combination, on thermoregulation during prolonged exercise

The effect of clinically used doses of propranolol, atenolol, nifedipine, propranolol plus nifedipine, and atenolol plus nifedipine on thermoregulatory responses of 11 healthy men was studied during 2-h block-stepping in heat. Drug intervention did not alter ventilation during exercise. In contrast, propranolol and atenolol produced equivalent reductions in exercise tachycardia, implying a similar level of beta 1-adrenoceptor blockade. The heart rate response to exercise was unaffected by nifedipine and during dual beta-adrenoceptor blockade and calcium antagonism was equivalent to that with beta-adrenoceptor blockade alone. While rectal temperature rises were not modified by drug ingestion, propranolol and, to a lesser degree, atenolol and combination therapy, but not nifedipine alone, attenuated skin temperature rises. Moreover, although atenolol, nifedipine, and their combination did not alter sweating, propranolol and its combination with nifedipine enhanced sweating during the 1st and 2nd h of exercise. This study concludes that nifedipine does not modify thermoregulation during exercise and allows for greater confidence of its use during cardiac rehabilitation. Furthermore, the present data confirm that propranolol does enhance sweating during exercise and demonstrate that this effect is not mediated simply by an earlier onset of rapid sweating nor abolished by concomitant calcium antagonism.

Safety of nizatidine in clinical trials conducted in the USA and Europe

The safety of nizatidine as treatment for active duodenal or gastric ulcer disease or as maintenance therapy following ulcer healing was assessed in 3800 nizatidine-treated individuals in clinical trials conducted in the USA and Europe. Safety parameters included physical examinations, electrocardiograms, eye examinations, serum chemistries and testosterone, hematology, and urinalyses. Adverse events were recorded without judgment of causality. Early discontinuations and adverse events, including complications of active duodenal ulcer disease, occurred more frequently in placebo-treated patients than in those given nizatidine. No differences were observed between the nizatidine and ranitidine treatment groups in regard to adverse event incidence or severity. Minimal changes in uric acid values were observed during ranitidine and nizatidine therapy. Abnormal liver function tests occurred infrequently and to an equal extent in nizatidine and placebo treatment groups. No clinically relevant differences in laboratory test results were observed between treatment groups in studies conducted in Europe.

Local effect of vasoactive intestinal polypeptide on human sweat-gland function

Physiological significance of vasoactive intestinal polypeptide (VIP), a putative co-transmitter of the cholinergic neuron innervating sweat glands, was investigated by its local effect on drug-induced sweating. VIP, methacholine chloride (MCH), or VIP plus MCH dissolved in 0.1 ml of 0.9% NaCl solution to a specified concentration was injected intradermally at the center of a forearm test area of 15 cm2 and the sweat rate was recorded continuously by capacitance hygrometry. In a cool environment (Ta, 23 degrees C), VIP failed to cause sweat secretion, but increased the rate of MCH-induced sweating, most markedly at a concentration of 10(-5) g/ml, where the rise in local skin temperature was the greatest. On an area anesthetized by nerve block in a hot environment (Ta, 35 degrees C), the effect was less obvious and less consistent, indicating that the sweat-facilitatory effect of VIP is reduced under the condition of passive cutaneous vasodilation. It may be postulated that VIP plays a role in securing ample oxygen supply to functioning sweat glands, especially with a relatively high cutaneous vasoconstrictor tone.

Effects of atropine on thermoregulatory responses to exercise in different environments

The thermoregulatory effects of atropine (2 mg im) were examined in six heat-acclimated subjects during exercise in three environments, which provided different evaporative capacities, but similar heat stress as indicated by the wet bulb, globe temperature index (WBGT). Subjects walked in environments of Ta = 42.3 degrees C, Tdp = 14.6 degrees C, WBGT = 29.1 degrees C (HD); Ta = 33.9 degrees C, Tdp = 23.5 degrees C, WBGT = 28.9 degrees C (WM); Ta = 30.4 degrees C, Tdp = 23.8 degrees C, WBGT = 27.4 degrees C, (WW) after atropine and saline injections. In comparison to saline, atropine elevated rectal temperature (Tre) (p less than 0.05) in HD. Additionally, atropine elevated (p less than 0.01) mean skin temperature (Tsk), and heart rate (HR) in all three environments relative to saline. Whole body sweating rate (msw) was 45% lower (p less than 0.01) in each environment after atropine relative to saline. Exercise time was reduced from saline values (p less than 0.05) by 26.5 min in the HD after atropine. Within the atropine treatments, Tre was higher (p less than 0.05) in HD (0.6 degrees C) than WW, and HR was higher (p less than 0.05) in HD (23 b X min-1) and WM (14 b X min-1) than WW. Tsk was higher (p less than 0.01) in WM than WW (1.2 degrees C) and in HD than WM (1.5 degrees C). Exercise time was 26.5 min longer (p less than 0.05) in WW than HD in the atropine experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic paroxysmal hemicrania. X. On the autonomic involvement

In four patients with chronic paroxysmal hemicrania, two of whom could precipitate attacks mechanically, various autonomic function tests were carried out in connection with attacks. Not all features could be studied in all patients. Forehead sweating and temperature were measured. Sweating, tearing, and nasal secretion were studied after systemic atropine administration, which reduced attack-related sweating, tearing, and nasal secretion markedly. Intra-ocular pressure was measured before and after the topical administration of an alpha-receptor blocking agent, thymoxamine. After topical thymoxamine no definite intra-ocular pressure increase occurred during precipitated attacks. In attacks precipitated by head movements, forehead sweating occurred seconds (up to 30 sec) before the pain. This study indicates that at least in some CPH cases, forehead sweating is not caused by the pain. Nor is the pain secondary to increase in intra-ocular pressure. The thymoxamine experiments seem to indicate that alpha-receptors in some way may be connected with the intra-ocular pressure increase during attack.

Somatosympathetic reflex unilateral sweating and pupillary dilatation in a paraplegic man

Sympathetic spinal reflex responses to painful stimuli have been studied in experimental animals, but have rarely been demonstrated in human beings. We report the case of a paraplegic man with a high thoracic sensory level to pain, who developed unilateral pupillodilatation and sweating from the head to the midthoracic region as a response to rib fractures below the sensory level. This regional sympathetic reflex response was similar in many ways to that seen in spinally transected animals. Regional sympathetic reflex responses may provide a clinically useful sign of a painful and perhaps dangerous condition which is located below the analgesic level in spinal cord-injured patients.

Quantitative analysis of the local effect of skin temperature on sweating

Effects of local skin temperature on sweat gland activity were analyzed quantitatively by measuring changes in the rates of thermal sweating and of drug-induced sweating by local heating. The data indicates that a rise in local temperature causes an accelerated increase in the rate of sweat production, the Q10 being around 2.5 regardless of the basal sweat rate with some individual variations. Local heating apparently facilitates transmitter release at the neuroglandular junction and augments glandular responsiveness, their significances being comparable.

Autonomic dysfunction in Parkinson's disease

We studied autonomic functions in 31 chronically treated patients with Parkinson's disease. They were tested twice: before a dose of medication and after medication. Before a dose of medication, when motor disability was maximal ("off"), patients had higher resting pulse rate, greater orthostatic fall in blood pressure, and decreased responses to Valsalva and cold pressor stimuli than their spouse-controls. To a heat stimulus, sweating was increased in the head and neck, and skin temperatures were cooler. After medication when function was optimal ("on"), the cardiovascular reflex abnormalities remained but were no worse. Skin temperature alterations and sweating abnormalities resolved.

Effects of dietary sodium on body and muscle potassium content during heat acclimation

It has been suggested that renal conversion of sodium (Na+) during training in hot environments results in potassium (K+) deficiencies. This investigation examined the influence of two levels of dietary Na+ intake (399 vs 98 mmol X d-1) on intramuscular, urinary, sweat, and whole body K+ homeostasis. Nine unacclimated, untrained males underwent heat acclimation during two 8 day dietary-exercise regimens (40.1 +/- 0.1 degrees C, 23.5 +/- 0.4% RH). Both diets resulted in depressed urinary K+ excretion. Sweat K+ and muscle K+ concentrations were not altered by diets or acclimation. The whole body stores of Na+ increased 31.1% (+916.8 mmol) during the high Na+ diet and decreased 7.8% (-230.4 mmol) during the low Na+ diet; whole body stores of K+ increased 4.1% (+137.6 mmol) during the high Na+ diet and increased 3.4% (+113.6 mmol) during the low Na+ diet. This dietary-acclimation protocol did not result in whole-body or intramuscular K+ deficits and offers no evidence to support previous claims that dietary sodium levels affect K+ balance.