The sarcoplasmic reticulum (SR) of smooth muscle is endowed with two different types of Ca2+ release channels, i.e. inositol 1,4,5-trisphosphate receptors (IP3Rs) and ryanodine receptors (RyRs). In general, both release channels mobilize Ca2+ from the same internal store in smooth muscle. While the importance of IP3Rs in agonist-induced contraction is well established, the role of RyRs in excit...

The aim of this study was to examine the morphological and functional changes in rabbit mesenteric arterial tissue cultured with fetal bovine serum. In the endothelium-denuded arteries cultured under a serum-free condition for one week (serum-free arteries), morphology of the smooth muscle layer was intact. In the serum-free arteries, high K+ -induced contraction did not change but norepinephri...

The p21-activated protein kinases (PAKs) have been implicated in cytoskeletal rearrangements and modulation of non-muscle contractility. Little, however, is known about the role of the PAK family members in smooth muscle contraction. Therefore, we investigated the effect of the predominant isoform in vascular smooth muscle cells, PAK1, on contraction and phosphorylation of the regulatory light ...

Na-Ca exchange is proposed to be an important regulator of myoplasmic intracellular Ca concentration ([Ca]|) and contraction in vascular smooth muscle. We investigated the role of Na-Ca exchange in regulating [Ca], in swine carotid arterial tissues that were loaded with aequorin to allow simultaneous measurement of [Ca], and force. Reversal of Na-Ca exchange, by reduction of extracellular Na co...

Excitation-contraction (EC) coupling in striated muscles is mediated by the cardiac or skeletal muscle isoform of voltage-dependent L-type Ca(2+) channel (Ca(v)1.2 and Ca(v)1.1, respectively) that senses a depolarization of the cell membrane, and in response, activates its corresponding isoform of intracellular Ca(2+) release channel/ryanodine receptor (RyR) to release stored Ca(2+), thereby in...

DETAR, REED, AND DAVID F. BOHR. Oxygen and vascular smooth muscle contraction. Am. J. Physiol. 214(Z): 241-244. 1968.-Oxygen tension is an important determinant of the contractile tension developed by isolated helical strips of rabbit aorta. A decrease in PO:! below 100 mm Hg causes the contractile response to epinephrine (l-3 pg/liter) to diminish linearly to near zero levels at < 1 mm Hg. If ...

Structures with the characteristics of molecular myosin were identified by electron microscopy in tissue sections of vertebrate smooth muscle. No thick filaments of myosin were found regardless of preparative procedures, which included fixation at rest and in contraction, glycerine extraction, and storage at low pH prior to fixation. Absence of thick myosin filaments and presence of what appear...