The K+ liquid ion exchange electrode system: responses to drugs and neurotransmitters

K+-sensitive liquid ion exchange electrode systems respond with a slow potential change to acetylcholine, choline, anticholinergic drugs, biogenic amines, and glutamic acid. The response threshold has been defined, and in most cases it is at extremely low concentrations (10(-7)-10(-5)M). The direction of the potential change varies, but in most instances it is additive to that produced by external K+. The K+ electrode system is further sensitive to decreasing pH, within a narrow and possibly physiological range of pH. These findings suggest that small measured changes in extracellular K+ are biased by the chemosensitivity of the liquid ion exchange electrode system to some compounds of physiological importance.

"Abnormal" responses of ejection fraction to exercise, in healthy subjects, caused by region-of-interest selection

We performed serial exercise equilibrium radionuclide angiography in eight normal subjects with each subject executing three tests: control, after nitroglycerin, and after propranolol. The left-ventricular ejection fraction (EF) was calculated by two methods: (a) fixed region-of-interest (FROI) using a single end-diastolic ROI, and (b) variable region-of-interest (VROI) where an end-diastolic and end-systolic region of interest were used. Abnormal maximal EF responses occurred in five of eight subjects during control using FROI but in zero of eight employing VROI (p < 0.05). After nitroglycerin, three of eight subjects had abnormal responses by FROI, but zero of eight were abnormal by VROI (p < 0.05). After propranolol, blunted EF responses occurred in three of seven by both methods. Falsely abnormal EF responses to execrise RNA may occur due to the method of region-of-interest selection in normal subjects with normal or high ejection fractions.

Angiography with epinephrine and beta receptor blocker in diagnosis of sigmoid lesions

Various sigmoid lesions, seen on barium enema of 39 patients, were investigated with angiography of the inferior mesenteric artery using three series. The first was performed with contrast medium only, the second after use of epinephrine, and the third after a beta-blocking agent (propranolol) combined with epinephrine. The patients were followed for more than three years. Eleven carcinomas were detected, all diagnosed angiographically. Carcinoma, radiation fibrosis, and diverticulitis with fibrosis may appear similar on pharmacoangiography, but the inflammatory reaction seen, for example in diverticulitis, is different. These findings are important because they can have an influence on the indications and selection of the most suitable operation to be performed.

The opiate antagonist naloxone does not consistently block inhibition of spinal nociceptive transmission produced by stimulation in lateral midbrain reticular formation of the cat

Electrical stimulation in the lateral midbrain reticular formation (LRF) inhibited the responses of spinal dorsal horn neurons to noxious (50 degrees C) skin heating. Systemic administration of naloxone (0.1-2 mg/kg) had no effect on inhibition produced by LRF stimulation in 10 units, while this inhibition was partially blocked in 3 units. The results indicate that endogenous opiates are not primarily involved in mediating descending inhibition from LRF stimulation.

Comparison of the alpha-adrenergic agonists, phenylephrine and methoxamine in rabbit papillary muscles

The positive inotropic effects of the alpha-adrenergic agonists, phenylephrine and methoxamine were compared in isolated rabbit papillary muscles. Phenylephrine in the presence of 10(-7)M propranolol produced a greater response than methoxamine. Antagonism by phentolamine was competitive for phenylephrine and apparently, noncompetitive for methoxamine. Based upon observed maximum following frequencies, 10(-4)M methoxamine had a greater cardiac depressant effect than 10(-4) phenylephrine. It was suggested that phenylephrine with a beta-adrenergic antagonist possessed advantages over methoxamine as an agonist for studying cardiac alpha-adrenergic receptors in rabbit papillary muscles.

Epinephrine-induced hypoaminoacidemia in normal and diabetic human subjects: effect of beta blockade

To evaluate the effect of epinephrine on the circulating amino acids, we infused epinephrine into normal human subjects and juvenile-onset diabetic patients given a constant basal infusion of insulin. Epinephrine infusion produced an identical 350--400 pg/ml rise in plasma epinephrine in both groups. In normal subjects, epinephrine caused a progressive 26% reduction in total circulating amino acids, despite unchanged levels of plasma insulin. This effect was most pronounced for the branched amino acids, which fell by 40% (P < 0.001). Plasma alanine was the only amino acid which failed to decline. Similarly, infusion of epinephrine in the insulin-infused diabetics produced a 23% fall in total amino acids, a 37% decline in branched chain amino acids, but no change in plasma alanine. Saline infusion in the insulin-infused diabetics had no effect on plasma amino acid concentrations. In addition, when epinephrine was infused into two insulin-withdrawn diabetics, a comparable hypoaminoacidemic response was observed. The infusion of propranolol in both normal and diabetic subjects totally prevented the epinephrine-induced fall in plasma amino acids. It is concluded that (1) increments in epinephrine similar to those observed in stress cause a decline in circulating amino acids (except alanine) which is greatest for the branched chain amino acids; (2) this hypoaminoacidemic effect occurs in the absence of a rise in plasma insulin and diabetic subjects, as well; and (3) epinephrine-induced changes in amino acid regulation are prevented by beta-adrenergic blockade. Our findings suggest that, in contrast with glucose and fat metabolism, epinephrine and insulin may have similar, rather than antagonistic, effects on plasma amino acid metabolism.

Effect of propranolol on aldosterone response to heat exposure in sodium-restricted men

To assess the role of the renin-angiotensin system in the control of aldosterone reease in response to heat exposure, 6 sodium restricted subjects were studied on three random experimental days: a control day and two heat exposure days (46C, 35 mbar, 90 min) with and without propranolol. Plasma aldosterone, renin activity, ACTH and K+ were determined from plasma samples taken every 20 min from 08:00 to 14:00. After propranolol administration, plasma aldosterone responsiveness to heat exposure increased, though plasma renin activity was depressed. Concurrently, propranolol reduced heat tolerance, leading to an increased ACTH and cortisol release in 3 of the subjects. Plasma levels of K+ were not significantly different during both heat exposure days. The enhanced response of plasma aldosterone may in part be related to the concurrent rises in ACTH, but a similar sustained aldosterone response was observed in subjects without ACTH release. Except for a significantly lower heart rate, propranolol induced no changes in hemodynamic and thermal response to heat. Plasma volume, blood pressure, sodium excretion, mean skin and rectal temperature rises and body weight losses were not modified by prior administration of the drug. The dissociation between aldosterone and renin activity after propranolol administration suggests that the aldosterone response to heat exposure is not primarily mediated by changes in activity of the renin-angiotensin system. Propranolol may lead to a reduced metabolic clearance rate of aldosterone or increase the sensitivity of the adrenal cortex to concomitant changes in the known stimuli, but the involvement of an additional factor in aldosterone regulation during heat exposure cannot be excluded.

Hormonal and metabolic studies in a patient with a pheochromocytoma

The metabolic and hormonal responses to oral glucose were studied in a patient with a pheochromocytoma before treatment, after alpha-blockade, after combined alpha- and beta-blockade, and after surgical removal of the tumor. Before treatment, fasting blood glucose was elevated [6.5 mmol/liter (117 mg/dl); normal range, 4.2--5.5 mmol/liter (75--100 mg/dl)], as was the fasting plasma nonesterified fatty acid level (1.19 mmol/liter; normal range, 0.06--0.7 mmol/liter), the blood total ketone body concentration (0.50 mmol/liter; normal range, 0.02--0.44 mmol/liter) and the lactate ot pyruvate ratio (16.2; normal range, 5.9--15.01. These abnormalities were corrected by alpha-adrenergic blockade alone and together with beta-blockade. Oral glucose tolerance (50 g) was mildly impaired in the untreated state, and the insulin response was decreased. Both alpha- and alpha- plus beta-blockade restored the insulin response to glucose but failed to correct the glucose intolerance. Three months after removal of the tumor, all metabolic findings were normal. The correction of the fasting metabolite concentrations and serum insulin levels by alpha-adrenergic blockade suggests that an alpha-adenergic effect causes the original metabolic abnormalities. The residual glucose intolerance after adrenergic blockade may result from incomplete blockade or factors other than alpha- and beta-adrenergic activity.

Follow-up hormonal controls on a HGH secreting pituitary adenoma. Pre- and postoperative study

The case of a 12 2/12-year-old boy with an HGH secreting eosinophilic adenoma is presented. The histologic investigation included conventional and ultrastructural techniques. The pre- and postoperative (1, 7, 11, and 20 months) hormonal controls are analyzed, indicating the persistence of HGH anteropituitary activity, even though surgical sectioning of the pituitary stalk was performed and the activities of thyroid, corticoadrenal and gonadotropin functions decreased. It is suggested that the hypothalamo-pituitary relationship may be maintained by extraportal venous circulations.

[Modern methods of evaluation of sinus node function by means of endocardiac electrophysiological study]

Atropine sulfate 0.04 mg/Kg i.v. and propranolol 0.2 mg/Kg i.v. were administered to patients with SSS in an attempt to determine intrinsic heart rate (IHR). Sinus node recovery time (SNRT) was determined before and after autonomic sympathetic and parasympathetic blockade. This method could distinguish SSS patients in two groups: group I was composed of patients with extrinsic sinus node dysfunction, group II was composed of patients with intrinsic sinus node dysfunction. We conclude that this differentiation is of great importance for clinical-prognostic evaluation and therapeutic program in SSS.

The metabolic and psychological effects of exercise training in hemodialysis patients

The effect of exercise training on metabolic abnormalities and psychological function was assessed in seven hemodialysis patients. Their initial work capacity was low and improved after 8 months of training. Exercise was associated with a reduction in the dose of antihypertensive medications in four patients and a decrease in phosphate binder therapy in three patients. There was also a rise in hematocrit levels (% delta = 34 +/- 20%, P less than 0.03) and the hemoglobin concentration (% delta = 37 +/- 23%, P less than 0.05) of five males. Plasma glucose levels fell (-5 +/- 2%, P less than 0.05, n = 5) and the glucose disappearance rate improved (20 +/- 7%, P less than 0.02), while hyperinsulinism decreased (-36 +/- 20%, P less than 0.02, n = 5) during training. There was no change in body weight or diet. Exercise lowered plasma triglyceride levels (-41 +/- 28%, P less than 0.02, n = 6) and raised the high-density lipoprotein cholesterol concentration (20 +/- 21%, P less than 0.05, n = 6). Psychological testing (n = 4) demonstrated that exercise training was associated with an improvement in depression, hostility, anxiety, social interaction, and outlook for the future. These results suggest that exercise can improve some of metabolic abnormalities and psychological dysfunction which exists in some dialysis patients.

[Role of alpha- and beta-adrenoreceptors in isolated guinea pig trachea anaphylaxis to aerosol tick (D. pteronyssinus) allergy]

Experiments were performed on inhalation-sensitized guinea-pigs, with the use of immunoallergic neurohistochemical techniques. Anaphylactic tracheobronchial spasm was shown to be related not only to the degree of sensitization but also to the state of alpha- and beta-adrenoreceptors. Sensitization, in its turn, changed the function of adrenoreceptors. It increased histamine sensitivity and decreased catecholamine sensitivity of an isolated organ.

Adrenergic receptor responses of vascular smooth muscle in Becker dystrophy. A muscle blood flow study using the 133Xe clearance method

The effect of intravenous adrenaline and of alpha and beta blockade on muscle blood flow in the tibialis anterior muscle of 8 normal subjects and 8 patients with the Becker form of X-linked muscular dystrophy has been assessed using the 133Xe clearance method. Whereas beta receptor responses to stimulation by adrenaline and blocking by propranolol did not differ significantly in the Becker patients and normal controls, the degree of alpha receptor blockade produced by phentolamine was significantly less in the Becker patients, suggesting a quantitative or qualitative abnormality of vascular alpha receptors. This pattern of response was not found in patients with spinal muscular atrophy or polymyositis. The possible significance of these findings is considered.

[Suppression, by beta-adrenergic receptor blockade, of the sympathomimetic component of dopamine renal action in water-saline depletion]

The effects of beta-adrenergic receptor blockade on the renal action of Dopamine (DA) in hydro-saline depletion were investigated in 9 healthy subjects. The beta-adrenergic blocking treatment was performed (Propranolol hydrochloride 2.4 mg/kg b.w. per day) during the 2 days preceding the renal function studies. For other experimental details, see our previous Note (11). In the presence of beta-adrenergic blockade DA effects in hydro-saline depletion consisted of: a) an increase in both RPF and GFR; b) a decrease in sodium abnormally isoosmotic reabsorption as % of sodium distal load; c) an increase in both sodium and osmolar clearances; d) an increase in free water clearance higher than that observed in the absence of blocking treatment. Therefore, the sympathomimetic effects of DA in hydro-saline depletion appear to be suppressed by beta-adrenergic blockade. It is suggested that such sympathomimetic action of DA may be mediated by beta-presynaptic receptors of noradrenergic nerve endings.

[Role of the sympathetic nervous system in the pathogenesis of experimental glaucoma]

It has been shown in experiments on rabbits that alpha-and beta-adrenoblockers, and lithium chloride solution exert different effect on intraocular tension of healthy animals with experimental glaucoma and transitory hypertension. The beta-blockker obsidan decreases the tension in experimental glaucoma. Pretreatment with the drug prevents the development of glaucoma. On the contrary, the alpha-blocker pirroxan promotes the development of glaucoma and does not elicit any hypotensive therapeutic effect. The drug-induced decrease in intraocular tension was recorded in healthy animals and in rabbits with transitory hypertensin of the eye. The hypotensive effect of lithium was noted only in the animals with experimental glaucoma. The role of alpha-and beta-adrenergic receiption in the pathogenesis of glaucoma is discussed.

[Compensatory ovarian hypertrophy during alloxan diabetes and adrenoreceptor blockade]

The sexual cycle ceases in rats with alloxan diabetes. Chronic administration of phentolamine promoted interruption of the sexual cycle while obsidan was conducive to its preservation in part of the animals. Most diabetic rats both given and not given adrenoblockers showed the complete absence of compensatory hypertrophy of the ovary (CHO). As shown by the analysis, the content of gonadotropins in the pituitary glands of diabetic rats was increased, with the response to chorionic gonadotropin being close to normal. It is suggested that the absence of CHO in most diabetic rats can be accounted for by the fact that after removal of one ovary the hypothalamohypophyseal system does not secrete gonadotropins in adequate amounts.