Dynamic Ca²⁺ signalling in rat arterial smooth muscle cells under the control of local renin‐angiotensin system

Abstract

Intracellular Ca¥ signals exhibit characteristic spatiotemporal patterns in various cell types and regulate a vast array of cell functions including cell movement, secretion, cell differentiation, cell death, gene expression and synaptic plasticity (Berridge, 1993). In vascular smooth muscle cells, the best known cell function regulated by the intracellular Ca¥ concentration ([Ca¥]é) is contraction, which controls blood pressure. Recent studies indicate that [Ca¥]é may also have a role in cell growth with activation of a phosphorylation cascade via the Ca¥-dependent prolinerich tyrosine kinase (PYK2) (Brinson et al. 1998;Sabri et al. 1998). Vascular smooth muscle cell proliferation is implicated in vascular diseases such as atherosclerosis. Although Ca¥ signalling mechanisms are often studied in isolated or cultured cells, it is also important to study Ca¥ signals within the context of the organized cell structure of tissues, because there exist intercellular interactions which may not yet be fully understood. With the above idea in

Ca2+ signaling in mouse mesenteric small arteries: myogenic tone and adrenergic vasoconstriction

“…These appeared similar to the "Ca 2ϩ ripples" ( Fig. 3Ba) reported previously in rat tail artery (1) and that have been attributed to activity of the intrinsic RAS system. Indeed, the angiotensin II competitive antagonist [Sar 1 , Ile 8 ]-ANG II (10 nM) abolished the ripples and caused a 9 Ϯ 1% decrease in MT.…”

“…The Ca 2ϩ signaling elicited by PE under this condition ( Fig. 4A; see "10PE_before_tone" movie in supplemental data) was similar to that we and others have reported previously for rat mesenteric small arteries (23,28,36), rabbit inferior vena cava (21,30), rat tail artery (1,8), and rat cerebral small artery (11). Briefly, upon exposure to PE (1-10 M), most vascular SMCs in the mouse mesenteric small arteries produced asynchronous propagating Ca 2ϩ waves, with the numbers of cells producing Ca 2ϩ waves and the frequency of the Ca 2ϩ waves being a function of the [PE] (Fig.…”

Mechanisms underlying angiotensin II-induced calcium oscillations

“…12B) to show that the average frequency was skewed by a few, very high values. Frequencies on the order of 0.1 Hz have also been measured in other vascular smooth muscle cells stimulated by ANG II (2,19). In contrast, the predicted frequency with the common-store model (when K ϩ channel inhibition is low enough that oscillations do occur) ranges from 0.03 Hz (if inhib K ϭ 75%) to 0.04 Hz (if inhib K ϭ 0%).…”

Pharmacological Modulation of Sarcoplasmic Reticulum Function in Smooth Muscle

“…Thus, smooth muscle tone is accompanied by a decrease in Ca 2ϩ spark frequency (Bonev et al, 1997;Mauban et al, 2001). Under certain conditions, which are not well defined, increased Ca 2ϩ spark activity generates oscillations that are comprised of repetitive Ca 2ϩ transients; these oscillations can then propagate as Ca 2ϩ waves (see Bradley et al, 2003 ripples and Ca 2ϩ flashes, as observed in individual smooth muscle cells within intact segments of rat tail artery (Asada et al, 1999). Ca 2ϩ ripples, which are modest in amplitude and frequency, are thought to be InsP 3 R-generated.…”