Comparison of contractile properties between slow and fast skeletal muscles of female diabetic Sprague-dawley rats

Objective: To compare isometric contraction, force-frequency relationship and muscle fatigue between slow and fast muscles of female type 2 diabetes mellitus Sprague-Dawley rats

Study Design: Experimental study

Place and Duration of Study: Physiology Department, Army Medical College, Rawalpindi and National Institute of Health, Islamabad from Jan to Dec 2015

Material and Methods: Twenty healthy female Sprague Dawley rats were divided into 2 groups with 10 rats in each group. Group-I [control] was fed with normal diet and group-II [diabetic] was given high fat diet. Group-II was given intraperitoneal streptozotocin [STZ] [35mg/kg body weight] on 15th day. Body weight, blood glucose and TG: HDL ratio were estimated on 21st day to confirm type II diabetes mellitus [T2DM] induction. Soleus and extensor digitorum longus [EDL] muscles were removed intact and fixed in organ bath system containing Krebs Ringer buffer solution and connected to data acquisition unit [iWorx] to study their contractile parameters

Results: Isometric twitch tensions of slow [soleus] and fast [EDL] muscles were similar in diabetic and control rats. Contraction and half relaxation times were slower in diabetic soleus muscles in comparison to control muscles. Diabetic soleus and EDL muscles displayed significantly [p<0.05] increased fatigability

Conclusion: In STZ induced type II diabetic slow muscles, the tetanic tension remains unaffected while contraction and half relaxation times were longer. In fast muscles, tetanic tension and the speed related properties remain unaffected. There was reduction in resistance to and recovery from fatigue in both slow and fast skeletal muscles

comparative study of the beneficial effects of ipratropium and beclomethasone against insulin-induced tracheal tissue contraction in a guinea pig model

To evaluate the acute effects of insulin on airway reactivity and the protective effects of beclomethasone and ipratropium against insulin-induced airway hyperresponsiveness on isolated tracheal smooth muscle in a guinea pig model. Materials and The trachea of each guinea pig was excised; one end of the tracheal strip was attached to the hook of the oxygen tube of a tissue bath and the other end was connected to a research-grade isometric force displacement transducer. The effects of varying concentrations of insulin [10[-7] to 10[-3]M] and insulin pretreated with a fixed concentration of beclomethasone [10[-6]M] and ipratropium [10[-6]M] on the isolated tracheal tissue were studied by constructing cumulative concentration-response curves. Changes in tracheal smooth muscle contractions were recorded on a 4-channel oscillograph. The means +/- standard error of the mean of the maximum amplitude of contraction with increasing concentrations of insulin and of insulin pretreated with fixed concentrations of beclomethasone and ipratropium were 35 +/- 1.13, 22 +/- 1.15 and 27.8 +/- 1.27 mm, respectively. The data showed that beclomethasone inhibited the contractile response of insulin to a greater extent than ipratropium. Thus we suggest that inhalational insulin pretreated with beclomethasone may be more efficacious than with ipratropium for the amelioration of potential respiratory adverse effects such as bronchoconstriction

Students' opinion on effectiveness of CBL in army medical college Rawalpindi, Pakistan

To assess students' opinion regarding group working, quality of learning and assessment in newly introduced case based learning at Army Medical College, Pakistan. Descriptive study. Army Medical College, 03 months. In this study, students from the second year MBBS class at Army Medical College were given a questionnaire on completion of their second year of medical school [2012] regarding their opinion about CBL. The questionnaire used in this study consisted of 18 statements with Likert-tyep responses ranging from Strongly Agree [1] to Strongly Disagree [5]. Statements were grouped using 3 categories: Group working, Quality of Learning and Assessment. Process of learning through group work and problem solving as a learning tool was appreciated by >80% of students. Also, >84% acknowledged that CBL has promplted them to come well prepared in the session and has helped them in improving their understanding of key concepts .>83% students opine that their efforts in CBL discussions are being evaluated fairly. Feedback from the students clearly asserts superiority of CBL in imparting knowledge, cultivating the habit of self-learning and inculcating skills of group discussions which is in consistence with the published literature. At the same time, weak point highlighted by the students need rectification

Serum levo-carnitine levels and skeletal muscle functions in type 2 diabetes mellitus in rodents

To study serum levo-carnitine [l-carnitine] levels and isometric contraction, force frequency relationship and fatigue of rodent skeletal muscles in type 2 diabetes mellitus. Randomized controlled trial. Physiology Department, Army Medical College, Rawalpindi, from January 2009 to January 2010. Sixty Sprague-Dawley rats were randomly divided into two groups; group I [control], fed on normal diet adlibitum and Group II [diabetic], fed on high fat diet and administered streptozocin to induce type 2 diabetes mellitus [T2DM]. At 21[st] day, plasma glucose and TG/HDL ratio were measured to confirm the development of T2DM in group II. At 28[th] day, blood was drawn by intracardiac puncture to estimate serum levo-carnitine levels. Contractile functions of skeletal muscles were assessed by using iWorx AHK/214 physiological data acquisition unit. Simple muscle twitches, maximum isometric twitch tension [MITT], time-to-peak twitch tension [TPTT] and time-to-relax to 50% of the peak twitch tension [1/2RT] of extensor digitorum muscles were recorded. Muscles were stimulated at higher frequencies to determine maximum fused tetanic tension [MFTT], maximum fused tetanic tension after fatigue protocol [TTFP] and recovery from fatigue [RF]. Serum levocarnitine level decreased significantly in the diabetic group. Both groups had similar MITT, TPTT and 1/2RT but decline in MFTT, TTFP and RF was significant in the diabetic rats. T2DM adversely affected serum levocarnitine levels and the contractile functions of rodent skeletal muscle at high frequency stimulation

Evaluation of oxidative stress, liver functions and anemia in lead intoxicated Sprague Dawley rats

To evaluate quantitative effect of lead exposure on the oxidative stress, liver functions and hematological profile. Seventy male healthy Sprague Dawley rats were randomly divided into two groups with thirty five rats in each group. Rats of lead intoxicated group were given weekly intraperitoneal injection of lead acetate 10 mg/kg body weight. After 6 weeks, intracardiac sampling was done and blood was used to determine hemoglobin concentration, erythrocyte count, red cell indices, serum MDA, serum ALT and AST levels. Lead intoxication of rats for 6 weeks revealed that serum MDA levels were increased to 7.8 +/- 0.48 micro mol/l [control = 3.2 +/- 0.27micro mol/l], ALT levels to 76.26 +/- 5.88 IU/l [control = 44.7 +/- 2.96] and AST levels to 258.06 +/- 13.30 IU/l [control = 156.8 +/- 5.04]. Hematological parameters of lead intoxicated group reveals lowered levels of hemoglobin, RBC count, MCHC and MCH while MCV remained statistically unchanged; manifesting hypochromic normocytic anemia. Lead intoxication for 6 weeks induces oxidative stress, hepatotoxicity and hypochromic normocytic anemia

Levo-carnitine reduces oxidative stress and improves contractile functions of fast muscles in type 2 diabetic Rats

Background: metabolic derangements in type 2 diabetes mellitus [T2DM] are likely to affect skeletal muscle contractile functions adversely. Levo-carnitine improves muscle contractile functions in healthy humans and rats and corrects metabolic derangements in T2DM. Therefore, it is likely to improve muscle contractile functions in T2DM as well. This study was designed to determine the effect of levo-carnitine on serum levo-carnitine levels, oxidative stress and contractile parameters of fast muscle in T2DM

Methods: ninety Sprague-Dawley rats were randomly divided into three equal groups. Healthy rats served as the controls, while T2DM was induced in diabetic and carnitine groups. The carnitine group was administered levo-carnitine 200 mg/kg/day intraperitoneally for 6 days. At 28[th] day, extensor digitorum longus muscles were removed and their functions were assessed using iWorx data acquisition unit [AHK/214]. Blood obtained by intra-cardiac sampling at 28[th] day was used for estimation of serum malondialdehyde [MDA] and levo-carnitine levels

Results: maximum isometric twitch tension, time-topeak twitch tension and time-to-relax to 50% of the peak twitch tension were not significantly different amongst the groups. Carnitine group showed significant improvement in maximum fused tetanic tension, maximum fused tetanic tension after fatigue protocol and recovery from fatigue after 5 minutes of rest period compared to the diabetic group. Serum MDA levels were reduced, while serum levo-carnitine levels were elevated significantly in carnitine group as compared to the diabetic group

Conclusion: levo-carnitine supplementation increases serum levo-carnitine levels which decreases oxidative stress. This action improves contractile force but delays fatigue in fast muscles of diabetic rats. Iran. Biomed. J. 17 [1]: 29-35, 2013

Contractile functions of slow and fast skeletal muscles in streptozotocin induced type 1 diabetic sprague dawley rats

To evaluate the contractile functions of slow and fast skeletal muscles in streptozotocin induced type 1 diabetic male Sprague Dawley rats. Randomized control trial. Department of Physiology, Army Medical College, Rawalpindi, from April 2010 to April 2011. Thirty healthy male Sprague Dawley rats were divided into two groups. The rats in group I [male control; n = 15] were fed on normal pellet diet and water ad libitum and received single intraperitoneal injection of normal saline at the start of study [day 1]. The rats in group II [male diabetic; n = 15] were fed on normal pellet diet and water ad libitum and rendered diabetic by single intraperitoneal injection of streptozotocin [STZ] 65 mg/kg body weight at the start of study [day 1]. Development of diabetes was confirmed within 72 hours by measuring blood glucose levels by glucometer. At the end of four weeks, i.e on day 29, dissection of slow soleus and fast extensor digitorum longus [EDL] muscles was carried out. These muscles were selected because they represent two distinctly different fiber type populations, that is, soleus [80% type I, 20% type IIA, 0% type IIB] and EDL [0% type I, 11% type IIA, 89% type IIB]. Their contractile parameters were recorded by iWorx advanced animal/human physiology data acquisition unit [AHK/214], including maximum isometric twitch tension, time to peak twitch tension, time taken to relax to 50% of the peak twitch tension, maximum fused tetanic tension, maximum fused tetanic tension after the fatigue protocol and tetanic tension after 5 minutes of rest period following the fatigue protocol. After four weeks, no significant difference was found when maximum isometric twitch tension [ITT] in isolated soleus and EDL muscles of the male diabetic group was compared with the control group. Time to peak twitch tension [TPT] and time taken to relax to 50% of the peak twitch tension [HRT] in isolated soleus muscle of the male diabetic group were significantly longer [p<0.001] as compared to the control group. On the contrary, TPT and HRT in isolated EDL muscle of the diabetic group were similar to the control group. Maximum fused tetanic tension in isolated soleus muscle of the diabetic group was similar to the control group. On the contrary, maximum fused tetanic tension in isolated EDL muscle of the male diabetic group was significantly lower [p<0.001] as compared to the control group. Maximum fused tetanic tension after the fatigue protocol and tetanic tension after 5 minutes of rest period following the fatigue protocol in isolated soleus and EDL muscles of the male diabetic group were significantly lower [p<0.001] as compared to the control group. Streptozotocin induced type 1 diabetes mellitus manifests differential effects on the contractile properties of slow and fast skeletal muscles of male Sprague Dawley rats.

Levo-carnitine normalizes blood glucose and lipid profile in insulin resistant type II diabetic rats

This study was planned to determine the effect of levo-carnitine on blood glucose and lipid profile in high fat diet fed, streptozotocin induced insulin resistant type II diabetic rats. Randomized controlled trial [RCT] Department of Physiology, Army Medical College, Rawalpindi from 20th to 15 Jan 2009. Ninety Sprague-Dawley rats were divided into three groups; each having 30 rats. Group I [control] was fed on normal diet while in Group II [Diabetic] diabetes was induced by feeding high fat diet and giving the injection of streptozotocin. Group III [Carnitine] was treated like group II to induce diabetes mellitus and later Levo-carnitine 200 mg/kg body weight/day was administered intraperitoneally for 6 days. The blood glucose and lipid profile were significantly deranged in the diabetic and carnitine groups as compared to the control. After levo-carnitine treatment the blood glucose level decreased significantly [p <0.001] in carnitine group [6.2 mmol/1] as compared to the diabetic group [22.7 mmol/1]. The levels of triglycerides, cholesterol and LDL were significantly decreased [P<0.001] in carnitine group 0.5 mmol/1, 1.3 mmol/1 and 0.2 mmol/1 as compared to the diabetic group 1.9 mmol/1, 4.4 mmol/1 and 3.1 mmol/1 respectively. HDL level was significantly raised [p<0.001] in the carnitine group [0.9 mmol/1] as compared to the diabetic group [0.4 mmol/1]. It is concluded that Levo-carnitine administration tends to normalize glycemic control and lipid profile in type II diabetes mellitus. However, human trial is recommended to ascertain its efficacy as an antidiabetic and antidyslipidemic agent for therapeutic use