Biomedical subjects

E Ekblad

Publications and source records attributed to E Ekblad.

93 records · Page 6Linked to original sources

PubMed1984

Neuropeptide Y co-exists and co-operates with noradrenaline in perivascular nerve fibers.

Neuropeptide Y (NPY)-immunoreactive nerve fibers were numerous around arteries and few around veins. NPY probably co-exists with noradrenaline in such fibers since chemical or surgical sympathectomy eliminated both NPY and noradrenaline from perivascular nerve fibers and since double staining demonstrated dopamine-beta-hydroxylase, the enzyme that catalyzes the conversion of dopamine to noradrenaline, and NPY in the same perivascular nerve fibers. Studies on isolated blood vessels indicated that NPY is not a particularly potent contractile agent in vitro. NPY greatly enhanced the adrenergically mediate contractile response to electrical stimulation and to application of adrenaline, noradrenaline or histamine, as studied in the isolated rabbit gastro-epiploic and femoral arteries. The potentiating effect of NPY on the response to electrical stimulation is probably not presynaptic since NPY affected neither the spontaneous nor the electrically evoked release of [3H]noradrenaline from perivascular sympathetic nerve fibers.

Animals↗

PubMed1984

GRP neurones in the rat small intestine issue long anal projections.

Gastrin releasing peptide (GRP) immunoreactive nerve fibres are numerous in the gut wall. Nerve cell bodies containing GRP are regularly found in the myenteric ganglia. The projections of GRP neurones in the rat small intestine were studied after myectomy or transection of the gut wall. Operated rats were left for 8-10 days or 5 weeks. Specimens were studied by immunocytochemistry, immunochemistry and in vitro for motor activity. GRP fibres were absent and GRP was markedly reduced in the gut wall underlying the area of myectomy and 10 mm anally to the myectomy or site of transection. Further anally, GRP and the GRP fibres gradually returned and were back to normal 25-30 mm from the lesion. Myenteric GRP neurones in the rat small intestine thus project anally over a distance of approximately 20-25 mm. A series of experiments was performed in order to test the idea that GRP is directly involved in intestinal motor functions. The results did not support this view. Strips of longitudinal smooth muscle with adherent myenteric ganglia were taken orally and anally to the myectomy and the motor activity of the specimens was compared. Electrical stimulation evoked a contractile response in the oral segment that was 6 times greater than that of the anal segment. However, GRP (10(-9)-10(-5) M) did not evoke contraction and the electrically induced contractile response was unaffected by GRP but could be blocked by atropine. The reduced contractile response in the 'denervated' anal segment is thus probably not due to a shortage of GRP fibres.

Animals↗

PubMed1984

Neuropeptide Y potentiates the effect of various vasoconstrictor agents on rabbit blood vessels.

The contractile effect of neuropeptide Y (NPY) was tested on isolated segments of basilar artery, central ear artery, gastro-epiploic artery and vein, and femoral artery and vein from the rabbit. At 30 nM NPY did not evoke vasoconstriction; at 300 nM NPY evoked a weak and variable response. NPY greatly potentiated the response of the gastro-epiploic and femoral arteries to noradrenaline without affecting the maximum response. As tested on the gastro-epiploic artery NPY was effective at concentrations of 1 nM and higher. As tested on the femoral artery the potentiating effect of 30 nM NPY on noradrenaline-evoked contractions was apparent immediately and 30 min after the application of NPY, but not after one hour. NPY (30 nM) potentiated the contractile response to noradrenaline and histamine but not to 5-hydroxytryptamine or high K+. The response to histamine was augmented in both arteries and veins, whereas the response to noradrenaline was enhanced in arteries but not in veins. NPY failed to potentiate the prostaglandin F2 alpha-evoked contraction except in the gastro-epiploic vein.

Animals↗