Norepinephrine Increases Alveolar Fluid Reabsorption and Na,K-ATPase Activity

The purpose of this study was to determine whether alpha-adrenergic receptor agonists have a role in alveolar fluid reabsorption, via Na,K-ATPase, in the alveolar epithelium. Alveolar fluid reabsorption increased approximately twofold with increasing concentrations of norepinephrine (NE) as compared with control rats. Treatment with the nonselective alpha-adrenergic receptor agonist, octopamine, and the specific alpha(1) agonist, phenylephrine, increased alveolar fluid reabsorption by 54 and 40%, respectively, as compared with control. The specific alpha(1)-adrenergic receptor antagonist, prazosin, inhibited the stimulatory effects of NE by approximately 30%, whereas alpha(2)-adrenergic antagonist, yohimbine, did not prevent the stimulatory effects of NE. The administration of ouabain, Na,K-ATPase inhibitor, prevented the NE-mediated increase in alveolar fluid reabsorption. In parallel with these changes, NE increased Na,K-ATPase activity and protein abundance in alveolar epithelial type II cells via the alpha(1)- and beta-adrenergic receptor. We report here that NE increased alveolar fluid reabsorption via the activation of both alpha(1)- and beta-adrenergic receptors, but not alpha(2)-adrenergic receptors. These effects are due to increased activity and abundance of the Na,K-ATPase in the basolateral membrane of ATII cells.

[Shy-Drager syndrome: a rare cause of orthostatic hypotension]

HISTORY AND ADMISSION FINDINGS

A 71-year-old man was admitted because of treatment-resistant orthostatic hypotension of unknown aetiology. When aged 64 years he developed some impotence and later urinary incontinence and urinary frequency. At 68 years he noted vertigo on physical activity, and a year later he had signs of reversible cerebral ischaemia. At this point the Schellong test demonstrated vasovagal circulatory dysfunction. After his 70th birthday the unsteadiness on walking and standing got worse and he had recurrent syncopes. He was in a wheel-chair when hospitalized and even the unsteady walk he could maintain for only a few seconds.

INVESTIGATIONS

Plasma and urinary concentrations of catecholamines were at the lower limit of normal but failed to increase during orthostasis. Hormonal, cardiological and infectious causes of the orthostatic hypotension were excluded. Orthostatic tests after Schellong and with the tilting table showed orthostatic hypotension without increased sympathetic activity but hypertensive blood pressure levels during the recumbent period. Intravenous infusion of norepinephrine produced an excess rise in blood pressure (raised norepinephrine sensitivity). The recurrent urinary infection was shown to be due to a hypotonic bladder detrusor muscle. Neurological examination revealed cerebellar dysfunction, signs of pyramidal tract abnormality and sensory polyneuropathy. A Shy-Drager syndrome was diagnosed on the basis of the history, absent blood pressure rise and lack of catecholamine release during orthostasis with increased epinephrine sensitivity and characteristic neurological signs.

TREATMENT AND COURSE

Physiotherapy and elastic stockings with administration of mineralocorticoids as well as of one direct (norfenefrine) and one indirect (amezinium) sympathomimetic drug failed to improve adequately the abnormal orthostatic response. But on additional administration of an alpha 2-receptor antagonist (yohimbine) the patient was able to stand and walk for a few minutes, but the urinary incontinence and the other neurological signs remained treatment-resistant.

CONCLUSION

If orthostatic hypotension occurs together with neurological symptoms, a Shy-Drager syndrome should be taken into account.

[Therapy of hypotension in pregnancy using norfenefrine hydrochloride with special reference to the effects on fetal circulation--initial observations]

Hypotension in pregnancy represents an often underestimated danger for mother and fetus. Several investigators have described an increased incidence of miscarriages, premature delivery and small for date babies. In a first study 10 pregnant women with hypotension and severe orthostatic dysregulation were treated with norfenefrine hydrochloride (3 x 45 mg p. os/day). To investigate the effects of this therapy we monitored maternal blood pressure, subjective well being, CTG and furthermore fetal circulation by using pulsed doppler sonography. An average 4.2 days of treatment were required for complete alleviation of symptoms. Blood flow volume and resistance-index were determined for the fetal aorta descendens, and were found to be the same as in normal pregnancies. In addition no difference in fetal outcome was seen and there was no occurrence of premature contractions.

A new beta 2-adrenoceptor agonist--D 2343--with long duration. Inhalation comparison with terbutaline in asthmatics

A new beta 2-adrenoceptor agonist D2343 has been shown in a human i.v. study to be less potent than terbutaline. Animal experiments showed an increased affinity to lung tissue and a longer bronchodilating effect than terbutaline when inhaled. In a randomized single-blind, crossover comparison, 2.5 and 5 mg D2343 and 5 mg terbutaline were inhaled by eight asthma patients. We found that 5 mg of D2343 was equipotent to 5 mg terbutaline in bronchodilatory effect measured with FEV1. The duration was longer with an increased bronchodilation (P less than 0.01) 6 h after D2343 inhalation compared with terbutaline. The mean fall in FEV1 3-6 h after inhalation was significantly greater with terbutaline than with D2343 (P less than 0.05). Thus, this study shows that inhaled D2343 has a longer bronchodilating effect than terbutaline.