These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Receptor-mediated C-kinase activation contributes to alpha-adrenergic tone in rat mesenteric resistance artery.
    Author: Drenth JP, Nishimura J, Nouailhetas VL, van Breemen C.
    Journal: J Hypertens Suppl; 1989 Sep; 7(4):S41-5. PubMed ID: 2553898.
    Abstract:
    Small branches from the superior mesenteric arteries (100-200 microns outer diameter) freshly dissected from male Wistar-Kyoto (WKY) rats were mounted for tension recordings. Some arterial rings were left in physiological salt solution and used as intact arteries while others were made permeable with alpha-toxin and incubated in cytoplasmic substitution solution. The relationship between ambient [Ca2+] and tension development during various modes of activation was measured in both intact and permeable arterial rings. The effects of ryanodine and 12-O-tetradecanoyl phorbol-13-acetate (TPA) were tested. Ryanodine had no effect on the tone developed in response to noradrenaline, but tension was increased when the tissues were bathed in 80 mmol/l K+ and [Ca2+] was raised (10 mmol/l). If it is assumed that ryanodine acts exclusively to enhance the permeability of the sarcoplasmic reticulum in smooth muscle, these data suggest that noradrenaline-induced tone is partly due to inhibition of Ca2+ buffering in the sarcoplasmic reticulum. However, this action of noradrenaline is not as pronounced in the resistance arteries as it is in the rabbit aorta. 12-O-tetradecanoyl phorbol-13-acetate had no effect on the noradrenaline-induced contractions of the intact resistance arteries, but caused a large leftward shift in the relationship between tension and extracellular [Ca2+] when high-K+ depolarization was the stimulus. This increased sensitivity to extracellular [Ca2+] could not be explained by stimulation of the Ca2+ influx. Instead, application of TPA to the rings made permeable with alpha-toxin dramatically increased the myofilament sensitivity to Ca2+, as demonstrated by a shift to the left of the tension-intracellular-[Ca2+] curve.(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]