Aims/hypothesis The first clinical manifestation of diabetes is polyuria. The prostaglandin E 2 (PGE 2 ) receptor EP 3 antagonises arginine vasopressin (AVP)-mediated water reabsorption and its expression is increased in the diabetic kidney. The purpose of this work was to study the contribution of EP 3 to diabetic polyuria and renal injury. -STZ mice also had increased protein expression of aquaporin-1, aquaporin-2, and urea transporter A1, and reduced urinary AVP excretion, but increased medullary V2 receptors. In vitro microperfusion studies indicated that Ep 3 −/− and WT-STZ CDs responded to AVP stimulation similarly to those of wild-type mice, with a 60% increase in fluid reabsorption. In WT non-injected and WT-STZ mice, EP 3 activation with sulprostone (PGE 2 analogue) abrogated AVP-mediated water reabsorption; this effect was absent in mice lacking EP 3 . A major finding of this work is that Ep 3 −/− -STZ mice showed blunted renal cyclooxygenase-2 protein expression, reduced renal hypertrophy, reduced hyperfiltration and reduced albuminuria, as well as diminished tubular dilation and nuclear cysts. Conclusions/interpretation Taken together, the data suggest that EP 3 contributes to diabetic polyuria by inhibiting expression of aquaporins and that it promotes renal injury during diabetes. EP 3 may prove to be a promising target for more selective management of diabetic kidney disease.

PGE2 regulates glomerular hemodynamics, renin secretion, and tubular transport. This study examined the contribution of PGE2 EP1 receptors to sodium and water homeostasis. Male EP1-/- mice were bred with hypertensive TTRhRen mice (Htn) to evaluate blood pressure and kidney function at 8 weeks of age in four groups: wildtype (WT), EP1-/-, Htn, HtnEP1-/-. Blood pressure and water balance were unaffected by EP1 deletion. COX1 and mPGE2 synthase were increased and COX2 was decreased in mice lacking EP1, with increases in EP3 and reductions in EP2 and EP4 mRNA throughout the nephron. Microdissected proximal tubule sglt1, NHE3, and AQP1 were increased in HtnEP1-/-, but sglt2 was increased in EP1-/- mice. Thick ascending limb NKCC2 was reduced in the cortex but increased in the medulla. Inner medullary collecting duct (IMCD) AQP1 and ENaC were increased, but AVP V2 receptors and urea transporter-1 were reduced in all mice compared to WT. In WT and Htn mice, PGE2 inhibited AVP-water transport and increased calcium in the IMCD, and inhibited sodium transport in cortical collecting ducts, but not in EP1-/- or HtnEP1-/- mice. Amiloride (ENaC) and hydrochlorothiazide (pendrin inhibitor) equally attenuated the effect of PGE2 on sodium transport. Taken together, the data suggest that EP1 regulates renal aquaporins and sodium transporters, attenuates AVP-water transport and inhibits sodium transport in the mouse collecting duct, which is mediated by both ENaC and pendrin-dependent pathways.

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Benign spasms of infancy (BSI), previously described as benign non‐epileptic infantile spasms or benign myoclonus of early infancy, are non‐epileptic movements manifesting during the first year of life and spontaneously resolving in the second year of life. BSI are characterized by spasms typically lasting 1–2 seconds, involving, to varying degrees, the head, neck, trunk, shoulders and upper extremities. Ictal and interictal EEG recordings are normal. BSI are not associated with developmental regression and do not require treatment. Distinction between BSI and infantile epileptic disorders, such as epileptic spasms or myoclonic epilepsy of infancy, can be challenging given the clinical similarities. Moreover, interictal EEGs can be normal in all conditions. Epileptic spasms and myoclonic epilepsy require timely treatment to improve neurodevelopmental outcomes. We describe a six‐month‐old infant presenting with spasm‐like movements. His paroxysms as well as a positive family history for epileptic spasms were in keeping with a likely diagnosis of West syndrome. Surprisingly, ictal video‐EEG did not reveal epileptiform activity, and suggested a diagnosis of BSI. We emphasize that ictal video‐EEG is the gold standard for classification of infantile paroxysms as epileptic or non‐epileptic, thereby avoiding over‐treatment for BSI and facilitating timely targeted treatment of infantile epilepsies. [Published with video sequences]

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