Pharmacological research : the official journal of the Italian Pharmacological Society
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Endothelin-1 (ET-1) is a pain mediator, elevated in skin after injury, which potentiates noxious thermal and mechanical stimuli (hyperalgesia) through the activation of ET(A) (and, perhaps, ET(B)) receptors on pain fibers. Part of the mechanism underlying this effect has recently been shown to involve potentiation of neuronal TRPV1 by PKCɛ. However, the early steps of this pathway, which are recapitulated in HEK 293 cells co-expressing TRPV1 and ET(A) receptors, remain unexplored. ⋯ However, in HEK 293 cells with low endogenous ET(A) mRNA levels, ET-1 does not induce a transient increase in [Ca(2+)](in). Observation of the [Ca(2+)](in) elevation in ND7/104 and HEK 293T cells in the absence of extracellular calcium suggests that ET-1 elicits a release of calcium from intracellular stores, and pretreatment of the cells with pertussis toxin or a selective inhibitor of phospholipase C (PLC) point to a mechanism involving Gαq/11 coupling. These results are consistent with the hypothesis that a certain threshold of ET(A) receptor expression is necessary to drive a transient [Ca(2+)](in) increase in these cells and that this process involves release of calcium from intracellular stores following Gαq/11 activation.
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The lack of availability of appropriate medicines for children is an extensive and well known problem. As a consequence off label or unlicensed administration of medicinal products in every day paediatric practice is frequent. A variety of obstacles hinder the development of paediatric indications for drugs primarily intended for the adult market. ⋯ The objective of the Paediatric Regulation is to improve the development of high quality and ethically researched medicines for children aged 0 to 17 years, to facilitate the availability of information on the use of medicines for children, without subjecting children to unnecessary trials, or delaying the authorisation of medicines for use in adults. The impact of the Paediatric Regulation reflects in an increase in the number of paediatric studies to be performed, even if a significant number of these studies have not started yet. The objective of this review is to describe the main regulatory and scientific features which play a role in the complex issue of paediatric drug development.