Differentiation of Calcium Activation Mechanisms in Vascular Smooth Muscle by Selective Suppression with Verapamil and D 600

Golenhofen, K.; Hermstein, N

doi:10.1159/000158036

Cited by 38 publications

(29 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…24 ' u The initial fast part of the contraction appears regulated by a Ca + + influx process different from that controlling the slow tonic part of the contraction. 26 Contractions activated by K + and sensitive to D600, and those stimulated by alpha-adrenoceptor activation and relatively resistant to D600 are associated with two separate Ca + + entry pathways, a potential and receptor operated channel, respectively.…”

Section: Discussionmentioning

confidence: 99%

Effects of oxygen and glucose deprivation on vasoactivity in isolated bovine middle cerebral arteries.

Vinall¹,

Simeone²

1986

Stroke

View full text Add to dashboard Cite

SUMMARY The effects of oxygen and glucose deprivation on vasoactivity were investigated using helical strips of bovine middle cerebral artery. Hypoxla, created by reducing the PO 2 of the bath, or oxidative inhibition with 2,4 dinitrophenol (DNP) or sodium azide, significantly reduced contractions induced by serotonin. Normal tonic contractions induced with fresh and aged whole blood, or 5-HT became phasic and qukkly relaxed to baseline in a hypoxic environment.Glucose elimination from the Krebs medium, or the inhibition of the glycolytic pathway with iodoacetic add (IAA), did not significantly reduce serotonin-induced contractions. However, contractions were inhibited more with the combination of oxygen and glucose deprivation, or DNP + IAA, than with oxygen deprivation alone. Efforts to produce rigor hi this preparation by oxygen/substrate reduction or metabolic Inhibition were unsuccessful.Tonic contractions induced by 70 mM potassium became phasic as the Ca + + concentration was reduced. Contractions resulting from the readdition of C a + + to arteries exposed to calcium-free high potassium solution were significantly reduced in the presence of oxidative and/or glycolytic inhibitors. The uptake of 45Ca + + , as measured by the lanthanum technique, decreased as the bath PO 2 was reduced in both serotonin stimulated and unstimulated arteries. Glucose deprivation alone did not affect 45Ca + + uptake. This study suggests that hypoxia has a direct inhibitory affect on cerebral vasoactivity mediated by reductions in sarcoplasmk Ca + + uptake. Stroke Vol 17, No 5, 1986 CORONARY '• 2 AND CEREBRAL 3 ' 4 vasospasm are an established cause of myocardial and cerebral ischemia. This ischemia is the result of reduced blood flow secondary to arterial contraction and increased vascular resistance. These constricted arteries are also subjected to this secondary ischemia, which may prolong the spasm.Most in vitro smooth muscle studies 5 " 7 have indicated that hypoxia and/or substrate depletion can reduce vasoactivity. This reduced activity may be the direct result of reduced influx of calcium into the sarcoplasma.8 Vascular smooth muscle is also capable of developing rigor tension in response to more dramatic ischemic conditions. 9 "" This type of muscle rigor is defined as an increase in resistance to stretch associated with a loss of ATP." Such irreversible constrictions induced by stretch injury that do not require oxygen, and are not reversed by treatment with cyanide or by removal of calcium, have been demonstrated in the rabbit cerebral artery. 12The purpose of the following experiments was to explore the effects of oxygen and glucose reduction on contractions induced by whole blood and blood products (serotonin) in bovine middle cerebral arteries. Efforts were also made to induce rigor tension in response to metabolic depletion. 45Ca ++ uptake was measured in serotonin stimulated and unstimulated arteries in relation to glucose and oxygen availability. Findings are discussed with reference to the possible existence...

show abstract

Section: Discussionmentioning

confidence: 99%

Effects of oxygen and glucose deprivation on vasoactivity in isolated bovine middle cerebral arteries.

Vinall¹,

Simeone²

1986

Stroke

View full text Add to dashboard Cite

show abstract

“…On the other hand, this drug inhibited the spontaneous activity of the rat uterine muscle. The spontaneous contractions of both portal vein and uterine muscle of the rat are dependent on extracellular Ca2+ (23)(24)(25). It has been suggested that flunarizine specifically inhibited increase in the availability of activator Call due to exogenous triggering of the vascular smooth muscle cells, but did not interfere with the potency in producing myogenic activity (4,5).…”

Section: Discussionmentioning

confidence: 99%

Selective Abolition Of Ca-Dependent Responses Of Smooth And Cardiac Muscles By Flunarizine

Nakayama

Kasuya

1980

Japanese Journal of Pharmacology

View full text Add to dashboard Cite

Abstract-The inhibitory effect of flunarizine on the Ca-dependent responses was compared with that of verapamil in isolated smooth and cardiac muscles.Flunarizine at a small dose shifted to the right the dose-response curve for Ca2+ of the phasic con traction due to electric stimuli in rabbit basilar strips, while in a large dose, flunarizine reduced the maximum tension and slope of the dose-response curve.The high Kinduced vasoconstriction of the rabbit basilar artery was inhibited by flunarizine. However, the action of flunarizine was about 30 times slower than findings with verap amil. The spontaneous activity of the rat portal vein was less susceptible to flunarizine, whereas that of rat uterus was completely inhibited by flunarizine.

show abstract

“…(Bilek, Laven, Peiper & Regnat, 1974;Golenhofen & Hermstein, 1975), peristatic contractions in the guinea-pig ureter (Golenhofen & Lammel, 1972) and acetylcholine contractions in the dog trachea (Farley & Miles, 1978). As verapamil has local anaesthetic activity in high concentrations (Haeusler, 1972;Singh & Vaughan Williams, 1972), it was suggested that inhibition of methoxamine-induced rythmic contractions in the rat vas deferens might be due to this (Hay & Wadsworth, 1980 Responses to KCI were inhibited by lower concentrations (50%7o inhibition of the tonic component occurred with verapamil 0.35 Ag/ml or nifedipine 0.01 ,ug/ml).…”

Section: When 15t [85sr]-labelled Microspheres Werementioning

confidence: 99%

Proceedings of the British Pharmacological Society

1981

British J Pharmacology

View full text Add to dashboard Cite

Differentiation of Calcium Activation Mechanisms in Vascular Smooth Muscle by Selective Suppression with Verapamil and D 600

Cited by 38 publications

References 9 publications

Effects of oxygen and glucose deprivation on vasoactivity in isolated bovine middle cerebral arteries.

Effects of oxygen and glucose deprivation on vasoactivity in isolated bovine middle cerebral arteries.

Selective Abolition Of Ca-Dependent Responses Of Smooth And Cardiac Muscles By Flunarizine

Proceedings of the British Pharmacological Society

Contact Info

Product

Resources

About