Salbutamol and chronic low‐frequency stimulation of canine skeletal muscle.

Abstract

1. The effect of simultaneous application of chronic muscle stimulation and salbutamol on the expression of mRNAs and proteins normally expressed by fast- or slow-twitch fibres was followed and the effects of changes in protein expression on mechanical performance were evaluated. Chronic low-frequency stimulation increased the myosin heavy chain (HC)-I level in the canine latissimus dorsi muscle and simultaneous administration of salbutamol partially blocked this change. Associated with the increase in HC-I level was a decrease in the velocity of shortening at zero load, VMAX. The change in VMAX was partially blocked by salbutamol. 2. Chronic low-frequency stimulation increased the levels of slow-twitch cardiac isoform sarco-/endoplasmic reticulum Ca(2+)-ATPase (SERCA2a) and phospholamban mRNA, and SERCA2a and phospholamban protein expression. These changes were associated with an increase in time-to-peak tension and a decrease in fusion frequency. Simultaneous administration of salbutamol blocked these changes in protein expression and muscle mechanics. Chronic stimulation of latissimus dorsi decreased the levels of the fast-twitch isoform of sarco-/endoplasmic reticulum Ca(2+)-ATPase (SERCA1a) and increased SERCA2a protein expression and decreased calcium uptake rate by muscle homogenates. These changes were blocked by salbutamol. 3. The loss of latissimus dorsi muscle weight by chronic stimulation was partially blocked by salbutamol.

β2-Agonist administration increases sarcoplasmic reticulum Ca2+-ATPase activity in aged rat skeletal muscle

“…Similarly, our findings show that fenoterol treatment increased SERCA1 protein levels in the RG and WG muscle of both adult and aged rats. Furthermore, we (22) have previously shown that fenoterol treatment can reverse age-related muscle wasting and weakness, a finding that is similar in some respects to another study (10), where salbutamol treatment attenuated the muscle atrophy usually associated with CLFS. The results of the present study show that fenoterol treatment reverses the age-related decrease in both the rate of relaxation and the V max of SERCA activity, a finding similar to salbutamol treatment attenuating the prolongation of contraction and the depression in SR Ca 2ϩ resequestration concomitant with CLFS (10).…”

“…Salbutamol treatment also increased the rate of SR Ca 2ϩ resequestration, which suggested that changes in skeletal muscle contractile parameters were mediated by alterations in SR proteins, namely a ␤ 2 -agonist-mediated induction of SERCA1 protein levels (36). In addition, salbutamol treatment attenuated the fast twitch-to-slow twitch transformation of myosin heavy-chain (MHC) isoforms, SR protein characteristics, and muscle mechanics that accompany chronic lowfrequency stimulation (CLFS) (10). Therefore, it is possible that ␤ 2 -agonist administration could attenuate an age-related decrease in skeletal muscle relaxation rate by reversing agerelated modifications of SR proteins.…”

The effect of PVDF‐TrFE scaffolds on stem cell derived cardiovascular cells

“…However, transient duration, as expressed by T 50 , was significantly longer for mES-CM cultured on scaffolds compared to mES-CM cultured in 2D. It is possible that culture on PVDF-TrFE scaffolds increases phospholamban production by mES-CM, which would inhibit SERCA and slow the reuptake of free Ca 2þ ions as shown in canine skeletal muscle with constant low frequency stimulation (Hu et al, 1996). In addition, caffeine-induced Ca 2þ release by mES-CM suggests that these cells have functional SR release through the RyRs, which is essential for normal Ca 2þ -induced Ca 2þ release and excitation contraction coupling (Liu et al, 2007;Satin et al, 2008).…”

Salbutamol and the Conditioning of Latissimus Dorsi for Cardiomyoplasty

“…In contrast to the androgenic steroids, Hu et al [10] found that salbutamol did not promote the slow-twitch phenotype in muscles subjected to CLFS. It partially blocked the switch to the slow-twitch phenotype.…”

“…[13]. The fiber-type distribution in muscles from salbutamol-treated dogs subjected to CLFS was 28%, type I; 60%, type IIa; and 12%, type IIx [10].…”