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Biomedical subjects

G D Lord

Publications and source records attributed to G D Lord.

10 recordsLinked to original sources
PubMed1980

Effects of low doses of clonidine in the monkey cranial circulation.

Migraine therapy using low doses of clonidine has been based on the proposal that clonidine directly inhibits vascular smooth muscle reactivity. In anaesthetized monkeys in which internal and external carotid vascular resistances were measured, the only significant effects of clonidine administered acutely (0.5 and 2 microgram x kg-1 i.v.) or chronically (2 microgram x kg-1 i.m. daily for 7 days) on cranial vascular responses to the constrictors noradrenaline and 5-hydroxytryptamine, and the dilators histamine, prostaglandin E1 and bradykinin, were small potentiations of some of the responses. Acute clonidine initially increased blood pressure and constricted the cranial vasculature, then induced hypotension without involvement of the cranial circulation. It also decreased the external carotid vasoconstrictor response to low frequency cervical sympathetic nerve stimulation. The low chronic dose of clonidine had no hypotensive effect. The pressor response to common carotid occlusion was inhibited by both acute and chronic clonidine. These experiments thus provide no evidence that clonidine inhibits cranial vascular reactivity at doses equivalent to those used in migraine.

Animals↗
PubMed1977

Complement activation in migraine.

Forty patients attending the Prince Henry Hospital migraine clinic have been investigated for evidence of complement activation related to migraine. These patients had a history of clinically similar migraine attacks. Levels of serum complement components were determined in nine patients, both in and out of migraine. Comparison of these levels showed significant reductions in C4 and C5 during headache. In a further 31 patients C3 breakdown products were sought when these patients were headache-free. They were detected in the plasma of three patients who proceeded to a migraine attack but not in the plasma of the remaining twenty-eight who did not. These findings suggest the presence of complement activation, which could explain many of the previously reported phenomena associated with migraine.

Complement C1↗