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Premise: The consequences of acidity for plant performance are profound, yet the prevalence and causes of low pH in bromeliad tank water are unknown despite its functional relevance to key members of many neotropical plant communities., Methods: We investigated tank water pH for eight bromeliad species in the field and for the widely occurring Guzmania monostachia in varying light. We compared pH changes over time between plant and artificial tanks containing a solution combined from several plants. Aquaporin transcripts were measured for field plants at two levels of pH. We investigated relationships between pH, leaf hydraulic conductance, and CO 2 concentration in greenhouse plants and tested proton pump activity using a stimulator and inhibitor., Results: Mean tank water pH for the eight species was 4.7 ± 0.06 and was lower for G. monostachia in higher light. The pH of the solution in artificial tanks, unlike in plants, did not decrease over time. Aquaporin transcription was higher for plants with lower pH, but leaf hydraulic conductance did not differ, suggesting that the pH did not influence water uptake. Tank pH and CO 2 concentration were inversely related. Fusicoccin enhanced a decrease in tank pH, whereas orthovanadate did not., Conclusions: Guzmania monostachia acidified its tank water via leaf proton pumps, which appeared responsive to light. Low pH increased aquaporin transcripts but did not influence leaf hydraulic conductance, hence may be more relevant to nutrient uptake., (© 2022 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

Premise: Because of its broad range in the neotropical rainforest and within tree canopies, the tank bromeliad Guzmania monostachia was investigated as a model of how varying leaf hydraulic conductance (K leaf ) could help plants resist and recover from episodic drought. The two pathways of K leaf , inside and outside the xylem, were also examined to determine the sites and causes of major hydraulic resistances within the leaf., Methods: We measured leaf hydraulic conductance for plants in the field and laboratory under wet, dry, and rewetted conditions and applied physiological, anatomical, and gene expression analysis with modeling to investigate changes in K leaf ., Results: After 7 d with no rain in the field or 14 days with no water in the glasshouse, K leaf decreased by 50% yet increased to hydrated values within 4 d of tank refilling. Staining to detect embolism combined with modeling indicated that changes outside the xylem were of greater importance to K leaf than were changes inside the xylem and were associated with changes in intercellular air spaces (aerenchyma), aquaporin expression and inhibition, and cuticular conductance., Conclusions: Low values for all conductances during drying, particularly in pathways outside the xylem, lead to hydraulic resilience for this species and may also contribute to its broad environmental tolerances., (© 2019 The Authors. American Journal of Botany is published by Wiley Periodicals, Inc. on behalf of the Botanical Society of America.)

The identification of recurrent or residual tumor tissue is sometimes complicated. The authors describe a 53-year-old woman in whom I-123 metaiodobenzylguanidine (MIBG) scintigraphy revealed a pheochromocytoma in the right adrenal gland. After the tumor was removed, the patient's catecholamine levels normalized. At the 3-month follow-up examination, I-123 MIBG scintigraphy did not reveal uptake in the right adrenal region but rather showed uptake in the left adrenal region. The patient's blood pressure remained in the normal range. A third scintigram, obtained 1 year after tumor resection, no longer detected I-123 MIBG accumulation in the left adrenal gland. These findings suggest that compensatory hyperplasia of the left adrenal gland led to enhanced uptake of I-123 MIBG. They also highlight the need for careful follow-up of such patients to distinguish between physiologic and pathologic processes.

Fabry's disease is an X-linked hereditary disorder resulting in accumulation of a glycolipid (galactosylgalactosyl glucosylceramide) due to deficiency of alpha-galactosidase A. The diagnosis can be made by histopathologic examination of skin biopsy, low activity of alpha-galactosidase in leucocytes and genetic examination. Treatment is symptomatic. We want to stress the multidisciplinary collaboration necessary to deal with this condition, in order to prevent acceleration of symptoms.

The comparative hemodynamic effects of dobutamine and dopamine were studied in 6 patients with low cardiac output resulting from acute myocardial infarction. Plasma levels of noradrenaline and renin were measured before and during a 5 microgram/kg/min infusion of each of the drugs. Dobutamine had a more pronounced chronotropic effect, increased the systolic arterial pressure more and decreased the systemic vascular resistance less than dopamine at doses which had comparable effects on cardiac output. Dobutamine stimulated renin release, which might partly be the cause of the increased systolic arterial pressure. The drug reduced the plasma level of noradrenaline, which might be explained as a reflex reduction in sympathetic tone. Dopamine, however, did not stimulate renin release but it did enhance the plasma level of noradrenaline, which might be due mainly to the release of endogenous noradrenaline.

In this study the results are presented of the haemodynamic and endocrinological inventarisation of 207 patients with essential hypertension. After establishing the relations of the various parameters with age (part IIA), interrelations between these variables are described (part IIB). The general finding is an increase in total peripheral vascular resistance early in the course of essential hypertension. In particular, this rise in resistance is found in the renal vasculature. In part III emphasis is given to the natural history of essential hypertension on the basis of a follow-up study. Again a rise in renal vascular resistance is found. As pointed out in the discussion (part IV) the cause of the abnormal resistance remains unknown. Emphasis is given to the renin-angiotensin system, which plays only a minor role. Here the factors regulating long-term renin secretion are discussed in favour of the baroreceptor theory.

The effect of an acute intravenous and repeated oral doses of propranolol on haemodynamics, plasma and urinary catecholamines and plasma renin activity was studied in patients with essential hypertension. Intravenous injection of propranolol 5 mg produced a fall in cardiac output but had no consistent effect on blood pressure. Treatment with oral propranolol for 24 weeks lowered cardiac output and blood pressure; total peripheral resistance did not differ from the pretreatment values. Neither acute intravenous nor chronic oral administration of the beta-blocker affected the resting plasma levels of noradrenaline and adrenaline. Long-term treatment with propranolol reduced urinary excretion of vanilmandelic acid without affecting urinary catecholamine excretion. Acute intravenous injection of propranolol decreased plasma renin activity less than did chronic oral treatment with the drug. The observed time course of plasma renin activity was compatible with the view that suppression of this enzyme contributed to the antihypertensive effect of propranolol.

1. Twenty-three subjects with essential hypertension were followed for a period of up to 7 years. They were untreated during the investigations. 2. Plasma renin concentration was found to decrease temporarily in some subjects. The ultimate change was a gradual rise. In those subjects who suffered myocardial infarction renin tended to rise more sharply. 3. A relationship was established with the rise in renal vascular resistance, which almost invariably occurred over the years.

The effects of the antihypertensive imidazoline compounds 2-(5 fluor-0-toluidine)-2-imidazoline hydrochloride (ST 600) and 2-(2, 6 dichlorophenylamine)-2-imidazoline hydrochloride (ST 155, catapres) on intra-arterial pressure, cardiac output, stroke volume, heart rate, total peripheral resistance, renal blood flow, glomerular filtration rate, renal vascular resistance, plasma volume, plasma renin and aldosterone concentration were studied in five patients with essential hypertension. The antihypertensive action of both compounds was similar and was accompanied by a reduction in heart rate and in cardiac output, total peripheral resistance being unchanged. There was no significant decrease in renal blood flow and glomerular filtration rate. Plasma volume and plasma concentrations of renin and aldosterone also did not change significantly. In the face of similar reductions in blood pressure, no differences were observed between cardio-renal haemodynamic responses after ST 600 and catapres. However ST 600 had a longer lasting effect (8-12 hours).

The effect of propranolol on diurnal variability of BP and plasma noradrenaline levels was assessed in 15 patients with uncomplicated essential hypertension. While total variability and average noradrenaline level remained unaltered, the pressor range (difference between basal and maximum BP readings) was reduced in most patients. An inverse relationship was observed between changes in pressor range and noradrenaline.

Physiologic studies were performed in 17 normotensive and 13 borderline hypertensive young male subjects, and repeated in 11 and 10 subjects, respectively, after two years. The criteria for normal blood pressure (systolic 120 mm Hg) and borderline hypertension (systolic 140 to 160 mm Hg) had been applied after a long introductory period of observation; nevertheless, the borderline hypertensive group turned out to be normotensive at the time of the second physiologic investigation. The main physiologic characteristics of the group with transient hypertension were overweight, increased total systemic vascular resistance, slightly decreased plasma and blood volume, slightly decreased plasma renin and noradrenaline levels, and significantly increased renal blood flow. Both overweight, increased vascular resistance, and increased renal blood flow persisted after normalization of blood pressure. A unifying concept is lacking.

1. The cardio-renal haemodynamic and endocrine effects of the anti-hypertensive agents 2-(2,6-dichlorophenylamine)-2-imidazoline hydrochloride (clonidine, St 155) and 2-(5-fluor-o-toluidine)-2-imidazoline hydrochloride (St 600) were investigated in twelve patients with essential hypertension. 2. The anti-hypertensive action of both compounds was similar and was accompanied by a reduction in heart rate and in cardiac output, total peripheral resistance being unchanged. There was no alteration in renal blood flow and glomerular filtration rate, and renal vascular resistance showed a significant decrease. Blood volume and plasma renin concentration did not change significantly. An inverse relation changes in plasma volume and plasma aldosterone concentration was observed. In the face of similar reductions in blood pressure, no differences were observed between systemic and renal haemodynamic and endocrine responses after clonidine and St 600.