Biomedical subjects

C H Fry

Publications and source records attributed to C H Fry.

93 records · Page 6Linked to original sources

PubMedDate not supplied

Placental corticotrophin releasing factor may modulate human parturition.

The interactions of corticotrophin releasing factor (CRF) and oxytocin on myometrial contractility were studied in isolated gestational myometrium in vitro. Acting alone oxytocin showed a significant dose related inotropic effect (P less than 0.001), whereas CRF did not. Dose-response curves of oxytocin in the presence of a fixed dose of CRF showed a threefold increase in the response to oxytocin without CRF present (P = 0.0019). When this combined priming and potentiating effect was investigated separately, priming of the myometrial strips with CRF prior to stimulation with oxytocin significantly enhanced the inotropic effect of oxytocin (P = 0.01) and when given together a significant potentiating effect was seen (P = 0.008). It is suggested that placental CRF may act as an important modulator of the inotropic effect of oxytocin on myometrium. The interaction between the two peptides may be similar to that which occurs between CRF and vasopressin in the anterior pituitary gland.

Corticotropin-Releasing Hormone↗

PubMedDate not supplied

Experimental models to study the physiology, pathophysiology, and pharmacology of the lower urinary tract.

The lower urinary tract is subject to a number of functional disorders, the most common of which, in humans, is bladder overactivity. To understand its pathophysiological basis, several in vitro and in vivo methodologies have been developed. In vitro tension recording from multicellular strips is in widespread use, and alternative experimental arrangements to a conventional organ bath are described, the relative merits are discussed, and the different experimentally derived variables are evaluated. Other methodologies, such as skinned fibres and whole bladder preparations, are also described. Electromyography in the isolated bladder is now feasible, and its potential uses discussed. The use of isolated smooth muscle cells is presented, especially with respect to the measurement of intracellular ion concentrations and electrophysiological parameters. The development of methods to prepare other cell types from the lower urinary tract is also introduced. A large-scale culture of urothelial and smooth muscle cells is possible, and their use as experimental tools, as well as a substrate for the development of surgical implants, is presented. Finally, different in vivo models of the lower urinary tract are presented, with reference to their investigation of clinical problems. These include models of bladder outflow obstruction, bladder ischaemia, bladder denervation, and congenital abnormalities and their influence on foetal development of the lower urinary tract.

Animals↗

PubMedDate not supplied

Use of ion-sensitive microelectrodes to study intracellular free magnesium concentration and its regulation in mammalian cardiac muscle.

Ion-sensitive microelectrodes (ISEs) have been used to measure intracellular [Mg2+] ([Mg2+]i) in cardiac muscle, although most measurements have tended to overestimate the value due to the poor selectivity of the Mg2+ ionophore in the sarcoplasm and to inaccurate collation of individual ISE measurements. This paper highlights the correct method for analysis of data from multiple ISE experiments. Since [Mg2+]i is constrained at a lower concentration than would be expected by passive distribution of the ion, some of the possible mechanisms underlying Mg2+ extrusion from ferret ventricular myocardium were investigated. During elevation of the extracellular [Mg], mean [Mg2+]i rose from 1.61 to 1.91 mM. The same intervention had no significant effect on membrane potential, intracellular [Na+] or pH measured with ISEs, and there was no change in resting [Ca2+], as assessed from fura-2 fluorescence. The data are not consistent with a simple mechanism for Na(+)-Mg2+ exchange as the primary mode of Mg2+ regulation in cardiac muscle or with an Mg2+ extrusion mechanism involving steady-state ion exchange.

Animals↗