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Biomedical subjects

M R Hanley

Publications and source records attributed to M R Hanley.

117 records · Page 7Linked to original sources
PubMedDate not supplied

Presence and actions of vasopressin-like peptides in the rabbit anterior uvea.

The presence of vasopressin-like immunoreactivity (VP-IR) in the rabbit eye was demonstrated by radioimmunoassay. Trigeminal nerve denervation resulted in a significant and selective decrease in the levels of VP-IR in the iris sphincter muscle and the cornea. The isolated iris sphincter muscle contracted in response to low concentrations of [Arg8]vasopressin (AVP) and related peptides. The V1 vasopressin receptor antagonist, d(CH2)5Tyr(Me)AVP, potently inhibited the contractile responses to AVP. AVP was found to induce an increase in the accumulation of inositol phosphates in the iris sphincter muscle but not in the dilator/ciliary body preparation in vitro. The present investigation demonstrates the presence of VP-IR in the rabbit eye and that this substance may be another sensory nerve-derived mediator acting on specific target sites in the anterior uvea.

Angiotensin Receptor Antagonists↗
PubMedDate not supplied

A vasopressin-like peptide in the mammalian sympathetic nervous system.

Vasopressin was among the first mammalian hormonal peptides to be identified and to have its structure determined. Its only undisputed physiological role is as a circulating neurohypophyseal antidiuretic hormone. Other notable effects of vasopressin on peripheral tissues include contraction of vascular smooth muscle, leading to elevation of blood pressure, and activation of glycogenolysis in liver. It has long been clear that vascular smooth muscle and hepatocytes are relatively insensitive to the low concentrations of vasopressin normally present in the circulation, and the physiological significance of their responses has therefore been in doubt. We now report that a new bioactive and immunoreactive vasopressin-like peptide (VLP) is widely distributed in the sympathetic nervous system of mammals, both in the principal noradrenergic neurones of ganglia and in nerve fibres innervating peripheral tissues. In addition to other peptides described in the mammalian sympathetic nervous system, VLP must be considered as a possible mediator of the non-adrenergic responses to sympathetic activation. Moreover, many of the effects previously attributed to circulating vasopressin may be neurally evoked.

Animals↗
PubMedDate not supplied

Occurrence and extracellular actions of inositol pentakis- and hexakisphosphate in mammalian brain.

Although inositol 1,3,4,5,6-pentakisphosphate (InsP5) and hexakisphosphate (InsP6) have been recognized for some time as naturally-occurring metabolites of inositol, their occurrence in mammalian cell types, including one of neural origin, has only recently been documented. This is of interest because of the recognized second messenger role of inositol 1,4,5-trisphosphate (InsP3) in intracellular signalling; coupling surface stimuli to cytoplasmic calcium discharge. The metabolism, existence in normal mature tissues, and possible functional roles of these inositol polyphosphates are unknown. Here we report evidence that InsP5 and InsP6 are synthesized in intact brain after labelling with [3H]inositol in vivo. We also show that local infusion of InsP5 and InsP6 into a discrete brain stem nucleus implicated in cardiovascular regulation, results in dose-dependent changes in heart rate and blood pressure.

Animals↗