The kidney is one of the main organs that produces ammonia and release it into the circulation. Under normal conditions, between 30 and 50% of the ammonia produced in the kidney is excreted in the urine, the rest being absorbed into the systemic circulation via the renal vein. In acidosis and in some pathological conditions, the proportion of urinary excretion can increase to 70% of the ammonia...

In larval Aedes aegypti, transcripts of the Rhesus-like glycoproteins AeRh50-1 and AeRh50-2 have been detected in the anal papillae, sites of ammonia (NH3/NH4+) excretion; however, these putative ammonia transporters have not been previously localized or functionally characterized. In this study, we show that the AeRh50s co-immunolocalize with apical V-type H+-ATPase as well as with basal Na+/K...

Yoshihiro Shiraiwa and Georg H. Schmid Universität Bielefeld, Fakultät für Biologie, Lehrstuhl Zellphysiologie, D-4800 Bielefeld 1, Bundesrepublik Deutschland Z. Naturforsch. 42c, 525—529 (1987); received December 5, 1986 Ammonia Excretion, Glycolate Excretion, Chlorella vulgaris, Photorespiration, pH-Effect The effect of pH changes on the excretion of ammonia and glycolate from algal cells int...

The excretion of ammonia is dependent upon several factors: the amount and duration of acid intake, presumably affecting variations in intracellular enzyme activity (1-3), the availability of precursors from which ammonia can be formed (4-6), and the pH of the urine (7-9). With respect to the effect of urine pH, the excretion of ammonia resembles that of a number of organic bases, such as quini...

Rh B glycoprotein (Rhbg) is a member of the Rh glycoprotein family of ammonia transporters. In the current study, we examine Rhbg's role in basal and acidosis-stimulated acid-base homeostasis. Metabolic acidosis induced by HCl administration increased Rhbg expression in both the cortex and outer medulla. To test the functional significance of increased Rhbg expression, we used a Cre-loxP approa...

Acidosis and angiotensin II stimulate ammonia production and transport by the proximal tubule. We examined the modulatory effect of the type 1 angiotensin II receptor blocker losartan on the ability of metabolic acidosis to stimulate ammonia production and secretion by mouse S2 proximal tubule segments. Mice given NH(4)Cl for 7 days developed metabolic acidosis (low serum bicarbonate concentrat...

The soil-dwelling nematode Caenorhabditis elegans is a bacteriovorous animal, excreting the vast majority of its nitrogenous waste as ammonia (25.3±1.2 µmol gFW(-1) day(-1)) and very little urea (0.21±0.004 µmol gFW(-1) day(-1)). Although these roundworms have been used for decades as genetic model systems, very little is known about their strategy to eliminate the toxic waste product ammonia f...

Rhesus (Rh) protein involvement in ammonia transport processes in freshwater fish has received considerable attention; however, parallel investigations in seawater species are scant. We exposed pufferfish to high environmental ammonia (HEA; 1 and 5 mmol l(-1) NH(4)HCO(3)) and evaluated the patterns of ammonia excretion and gill Rh mRNA and protein expression. Gill H(+)-ATPase, NHE1, NHE2, NHE3,...

Models of branchial transport in teleosts have been reshaped by the recent discovery of Rhesus (Rh) glycoproteins, a family of proteins that facilitate the movement of NH(3) across cell membranes. This study examines the effects of crowding and feeding on ammonia excretion in gulf toadfish (Opsanus beta) within the context of Rh glycoproteins and the ammonia-fixing enzyme, glutamine synthetase ...