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A BST RACT. --Temperature transduction in peripheral cold receptors and processing of peripheral temperature signals in the spinal cord were studied in cats and rats. The temperature dependence of the generator potential is attributed to different temperature coefficients of an electrogenic Na-effiux and the passive Na-influx. Cold receptor activity and particularly its bursting pattern is considerably modulated by the local Ca-concentration, but the effect of elevated Ca-concentration is abolished by the ATPase blocker ouabain. --The peripheral temperature signals from the scrotal skin of rats are transformed in dorsal horn neurones (DHN) into temperature reactions, which occur only above (warm reaction) or below (cold reaction) a certain temperature threshold and are limited to an operational range of 1-4°C. Convergency of different temperature inputs were observed in one and the same DHN. Supraspinal control of temoerature reactive DHN appears to be complex but predominantly excitatory.

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Mellander & Nordenfeldt' have shown by means of a water-filled plethysmograph that following the intravenous injection of dihydroergotamine (DHE) into normal subjects, there is vasoconstriction of the capacitance vessels in the lower limbs. At the same time they showed that the arterial resting flow was almost unaffected. The conclusion of their investigation was that DHE can be used in vasomotor disturbances of the capacitance vessels.In the present investigation, an air-filled rubber cuff plethysmograph was used to compare the effect of DHE and a new synthetic hydrogenated ergot alkaloid, dihydroergostine (DE 145-Sandoz), on the capacitance vessels and the resting blood flow in the lower extremities. Chemistry and pharmacology of dihydroergostine As seen in fig. 1, the chemical structure of DE 145 and DHE has the following components in common: DH-lysergic acid, L-Proline and L-Phenylalanine. The two compounds differ with respect to the composition of the «-hydroxyamino acid which binds the peptide half to the DH-lysergic acid. In the case of DE 145, the acid is a-hydroxy-a-aminobutyric acid, and in DHE this part of the alkaloid molecule consists of «-hydroxyalanine.Pharmacologically, there is also a certain resemblance between the two alkaloids. Both substances inhibit spontaneous or ergometrine-induced contractions of the rabbit uterus2. In spinal cats, a rise in blood pressure is seen after the intravenous administration of 10-50 tLg/kg, and both compounds produce a prolonged increase in tone in segments of freshly excised femoral vein from dogs. The «-adrenolytic effect of DE 145 is greater than that of DHE.2 2 The re-uptake of neuronally-released noradrenaline within the amine depots of the nerve endings is inhibited by both DE 145 and DHE. 2, 3 METHODThe investigation was carried out by means of an air-filled rubber cuff plethysmograph applied to the thickest part of the calf. The arterial resting flow was recorded during venous stasis, produced by means of a cuff placed just proximally to the patella.4 The changes in volume following medication, at UNIV OF MASSACHUSETTS on April 9, 2015 ang.sagepub.com Downloaded from

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