Membrane Properties and Excitatory Neuromuscular Transmission in the Smooth Muscle of Dog Cerebral Arteries

Abstract

1 Drug actions on electrical and mechanical properties of smooth muscle cells and neuromuscular transmission in the canine cerebral arteries were investigated by use of microelectrode and isometric tension recording methods. 2 In the basilar and middle cerebral arteries, the resting membrane potentials were -49.4 mV and -51.7 mV, respectively, the length constants 0.57mm and 0.45 mm, respectively and the time constants 142 ms and 118 ms, respectively. 3 Outward current pulses did not evoke the spike in either artery but did evoke the spike under conditions of pretreatment with 10mM tetraethylammonium (TEA). 4 The maximum slope of depolarization produced by a ten fold increase in [K]O plotted on a log scale was 40.1 mV in the basilar artery and 42.2 mV in the middle cerebral artery. 2-Nicotinamidoethyl nitrate, the K-permeability accelerator, had no effect on the membrane potential. 7 Perivascular nerve stimulation produced excitatory junction potentials (e.j.ps). Often e.j.ps were followed by a hyperpolarization. Repetitive stimulation produced facilitation after several stimuli and depression followed. In some cells, this depression appeared without facilitation.8 The e.j.ps ceased with pretreatment with guanethidine (10-6 M) or tetrodotox:n (3 x 10-7 M), while phentolamine (10-7 M) and yohimbine (10-7 M) enhanced the amplitude of e.j.ps. ATP (10-5 M) and noradrenaline (10-6 M) supressed and prazosin had little effect on the e.j.ps. Atropine (10-6 M) also had no effect on the e.j.ps. 9 Specific features of the cerebral artery and systemic vascular beds were compared, and the features of adrenoceptors on the smooth muscle membrane were compared with findings in other vascular beds.

Effects of adrenoceptor agonists and antagonists on smooth muscle cells and neuromuscular transmission in the guinea‐pig renal artery and vein

“…The responses of the vascular smooth muscle to catecholamine differs markedly with location and species (Ito, Kitamura & Kuriyama, 1979;Fujiwara et aL, 1982;Hirst, Neild & Silverberg, 1982). In the guinea-pig renal artery and vein, NA depolarized the membrane and slightly reduced the membrane resistance.…”

Purinergic Signaling and Blood Vessels in Health and Disease

“…ATP produced contraction of canine basilar artery (Muramatsu et al, 1980) and was later proposed to be released as a cotransmitter with NA from sympathetic nerve terminals (Muramatsu et al, 1981). Perivascular nerve stimulation of the guinea pig basilar artery elicited EJPs (Karashima and Kuriyama, 1981;Fujiwara et al, 1982). Receptors for ATP and adenosine were found at both pre-and postjunctional sites in canine cerebral artery (Muramatsu et al, 1983).…”

Voltage-Gated K+ Channel Dysfunction in Myocytes from a Dog Model of Subarachnoid Hemorrhage

“…There is a steep relation between cerebral artery diameter and resting membrane potential as deter- (Fujiwara et al, 1982;Knot and Nelson, 1998). Accordingly, we estimated how the degree of depolarization observed in vasospastic myocytes might affect the tone of vasospastic arteries using different [K + ] o .…”