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Open Access 
F u l l  L e n g t h  A r t i c l e  

 Inhibitory Effect of Sodium Cromoglycate on Insulin Induced 

Airway Hyper-Reactivity 
 

Mahjabeen Sharif 1, Bushra Tayyaba Khan 2, Fatima Qasim Malik 3, Muhammad Asim Anwar 4 

1 Assistant Professor Pharmacology, Army Medical College, National University of Medical Sciences (NUMS) Rawalpindi 
2 Associate Professor Pharmacology, Army Medical College/ National University of Medical Sciences (NUMS) Rawalpindi 

3 Senior lecturer, Department of Pharmacology & Therapeutics, Yusra Medical and Dental College Islamabad 
4 Consultant Physician PAEC General Hospital Islamabad  

A B S T R A C T  

Objective: To explore the acute effect of insulin on airway reactivity of guinea pigs and   protective effects of sodium 

cromoglycate against insulin induced airway hyper-reactivity on isolated tracheal tissues of guinea pigs in vitro. 

Subjects and Methods: Effects of insulin (10-7- 10-3 M) and insulin pretreated with sodium cromoglycate (10-6 M) were 

observed on isolated tracheal strip of guinea pig (n=12) in vitro by constructing cumulative concentration response 

curves. The tracheal smooth muscle contractions were recorded with Transducer on Four Channel Oscillograph. 

Results: Insulin produced a concentration dependent reversible contraction of isolated tracheal muscle of guinea pig. 

The mean ± SEM of maximum amplitudes of contraction with insulin and insulin pretreated with sodium cromoglycate 

were 35 ± 1.13 mm and 14.55 ± 0.62 mm respectively. Cromoglycate shifted the concentration response curve of insulin 

to the right and downwards. 

Conclusion: Sodium cromoglycate significantly reduced the insulin mediated airway hyper-reactivity in guinea pigs. So 

we suggest that pretreatment of inhaled insulin with cromoglycate may have clinical implication in amelioration of its 

potential respiratory adverse effects such as bronchoconstriction. 

Key words Bronchoconstriction, Inhaled insulin, Oscillograph, Sodium cromoglycate, Tracheal muscle. 

Author`s Contribution 
1, 

Conception, synthesis, planning of research 
and manuscript writing 
2
Interpretation and discussion Data analysis, 

3,4 
Interpretation,  manuscript writing and 

Active participation in data collection  

Address of Correspondence 
Mahjabeen Sharif 
Email: mahjabeen30@hotmail.com. 

Article info. 
Received:  August 25, 2017 
Accepted:  November 3, 2017 

Cite this article. Sharif M, Khan B.T, Malik F.Q, Anwar M.A. Inhibitory Effect of Sodium 
Cromoglycate on Insulin Induced Airway Hyper-Reactivity. JIMDC.2017;6(4): 

 

Funding Source: This research 
study was financially supported 
by National University of 
Sciences and Technology (NUST) 

Islamabad. 
Conflict of Interest: Nil 

I n t r o d u c t i o n  
 

The predominant mode of insulin administration is by 

subcutaneous injection.1 Injection related anxiety leads to 

poor compliance and suboptimal glycemic control.2,3 

Consequently alternative noninvasive inhalational route of 

insulin administration was approved in 2006.4 Inhalational 

insulin causes similar reduction in HbAIc and fasting 

blood sugar, compared with regular insulin and less risk of 

hypoglycemic episodes and weight gain.5 It increases 

patient’s satisfaction and improved patients compliance 

leading to improved glycemic control 6,7 Unfortunately its 

use was limited due to its potential to produce respiratory 

adverse effects such as increased bronchial reactivity, 

cough, dyspnea and bronchoconstriction.8  Insulin has 

long been recognized as pro-inflammatory and pro-

contractile hormone.9,10 The most likely mechanism of 

inhaled insulin induced bronchoconstriction is that insulin 

O R I G I N A L  A R T I C L E  



 

                           231 J I M D C   2 0 1 7  231 

increases the mast cells degranulation and subsequently 

increased release of histamine and contractile 

prostaglandins are responsible for allergic inflammation of 

airways.11-13 

It is well established from the review of literature that 

cromoglycate sodium exerts its anti-allergic and anti-

inflammatory effects due to its mast cell stabilizing 

activity.  Prophylactic use of sodium cromoglycate 

decreases the symptoms of airway hyper-reactivity 

induced by variety of allergens and chemicals. 

Cromoglycate sodium has also shown to have weak 

bronchodilatory effects in guinea pig airway models.14  

To our knowledge protective effects of sodium 

cromoglycate against inhalational insulin induced airway 

hyper-responsiveness have never been evaluated. Insulin 

induced tracheal muscle contraction in guinea pig model 

described in this study closely resembles the 

bronchoconstriction produced by pulmonary delivery of 

inhaled insulin as high concentration of insulin get 

deposited in airway smooth muscles in both cases.15 

Based on the pharmacological effects of sodium 

cromoglycate the present study was designed to evaluate 

the efficacy of sodium cromoglycate against insulin 

mediated airway hyper-reactivity of guinea pig in vitro. 

S u b j e c t s  a n d  M e t h o d s  

This experimental study was conducted in Pharmacology 

department in collaboration with Centre for Research in 

Experimental and Applied Medicine (CREAM) Army 

Medical College Rawalpindi from January 2012 to August 

2012. 

Total 12 healthy guinea pigs of either sex of Dunkin 

Hartely variety weighing 500-700g were used for current 

study.16 These guinea pigs were randomly divided into 

two groups; each group consists of 6 guinea pigs. All the 

protocols described in this study were approved by Ethics 

commitee of Centre for Research in Experimental and 

Applied Medicine (CREAM). They were sacrificed by 

cervical dislocation.17 The trachea was dissected out and 

tracheal chain was prepared with smooth muscle in the 

centre and cartilaginous portions on both sides. The 

tracheal strip was attached to the hook of oxygen tube of 

tissue bath containing oxygenated krebs-Henseleit 

solution at 37o C.18 Tracheal contractions were recorded 

with Research Grade Isometric Force Displacement 

Transducer Harvard Model No 72-4494 on four channel 

oscillograph Harvard Model No 50-9307.19 This Research 

Grade Research Grade Isometric Force Displacement 

Transducer Harvard Model No 72-4494 was extremely 

sensitive to force applied with very short amplitude. It has 

a minimum displacement of 0.1mm for a force application 

of 25 grams. 20 

Group 1: Cumulative concentration response curve of 

insulin (10-7 to 10-3 M)  

Cumulative dose response curves of insulin were 

constructed with varying concentrations (10-7 to 10-3M).  

When maximum response with 10-7 M concentration was 

obtained then the subsequent doses were added without 

washing the previous dose. 21 Four channel oscillograph 

was used for recording tracheal muscle contraction. This 

group served as control group 1 and dose response curve 

of insulin pretreated with cromoglycate was compared 

with that of insulin alone.  

Group 2: Cumulative concentration response curve of 

insulin in the presence of fixed concentration (10-6 M) of 

sodium cromoglycate. Cromoglycate sodium was added 

to the organ bath in a concentration of 10-6 M.14   After 15 

minutes, the successive doses of insulin ranging from10-7 

to 10-3 M were added into the organ bath in the presence 

of cromoglycate sodium. Cumulative concentration 

response curves pretreated with cromoglycate sodium 

were constructed.  

Statistical analysis 

The means of amplitudes of contractions and SEMs were 

calculated using SPSS version 16. Student t test was 

applied to determine the significant difference between 

two observations.  

p-value of less than 0.05 was considered as statistically 

significant.  

R e s u l t s  

Acute effects of insulin were studied on isolated tracheal 

smooth muscles of guinea pig by adding the successive 

doses of insulin ranging from 10-7 to 10-3 M. Insulin 

induced   contraction of tracheal smooth muscle was 

evident at a concentration of 10-7 M concentration. 

However, a significant enhancement of insulin-induced 

contractions was observed at 10-5 M, 10-4 M and 10-3 M 

concentration. (Figure 1).  



 

                           232 J I M D C   2 0 1 7  232 

 
Figure 1: Comparison of semi log concentration 

response curve of group 1 and group 2 on isolated 

tracheal smooth muscle of guinea pig. 

 Results are average of six separate experiments.  

 Data is represented as mean ± standard error of 
means (SEM) 

Changes in tracheal smooth muscle contractions were 

measured by taking the amplitudes of tracheal smooth 

muscle contraction. Amplitudes of contraction with 

maximum dose of insulin (10-3 M) was 35 ± 1.13mm 

(Table 1).  

So insulin significantly enhanced the myogenic airway 

smooth muscle tone. This insulin induced tracheal smooth 

muscle contraction was significantly reduced in sodium 

cromoglycate treated group from 35 ± 1.13mm to 14.55 ± 

0.62 mm. The means of amplitudes of contractions with 

varying doses of insulin when compared between group 1 

and 2 were found to be statistically significant (Table 1). 

Our data showed that maximum constrictor response of 

insulin in the presence of cromoglycate was reduced by 

41.57 percent as compared with insulin group (Table 1). 

Insulin concentration response curve in the presence of 

cromoglycate was shifted to the right and downwards   

indicating a profound inhibitory effect of cromoglycate 

sodium on airway hyper-reactivity induced by insulin 

(Figure 1). 

D i s c u s s i o n  

The present study demonstrated that insulin induced 

airway smooth muscle contraction of guinea pigs in a 

concentration range of 10-7 M to 10-3 M. These 

contractions were reversible and sustained in nature. 

Schaafsma et al also reported the acute contractile effect 

of insulin on isolated tracheal preparation of guinea pig 

but the concentration of insulin was in the range of 10-10 to 

10-5 M. 21 Our observations are also supported by in vivo 

studies in which treatment of diabetic rats with insulin 

resulted in airway hyper-reactivity and inflammation. This 

enhanced airway reactivity was due to the release of 

inflammatory mediators from mast cells under the 

influence of insulin. 22  

When isolated tracheal muscle was pretreated with 

sodium cromoglycate, the maximum percent response of 

insulin in the presence of cromoglycate sodium was 

reduced to 41.57 percent of insulin control. So 

cromoglycate sodium significantly ameliorated the insulin 

mediated airway hyper-reactivity. The protection offered 

by cromoglycate is presumably through the inhibition of 

release of contractile prostaglandins and histamine from 

mast cells of isolated tracheal strip. Our results are in 

accordance with other studies in which sodium 

cromoglycate has been shown to inhibit the 

bronchoconstrictor response to several kinds of 

challenges.23 

Table 1: Comparison of responses of isolated tracheal muscle of guinea pig between two groups 

Concentration 
of  insulin (M) 

Group 1 (n=6) 
Amplitude of 
contraction (mm) 
(mean ± SD) 

Group 2 (n=6) 
Amplitude of 
contraction (mm) 
(mean ± SD) 

p-value Percent response in 
group 1 from 
baseline to 10-3  M 
dose 

Percent response in 
group 2 from 
baseline to 10-3 M 
dose (group 1) 

10-7 8.167 ± 2.14 0 ± 0 .004* 23.34 0 

10-6 16.16 ± 2.48 0.5 ± 0.837 .007* 46.17 1.43 

10-5 26.1 ± 2.78 6.17 ± 1.169 0.000* 74.58 17.62 

10-4 31.8 ±  2.04 10.33 ± 1.63 .003* 90.86 29.5 

10-3 35 ±  2.76 14.55 ±1.52 .004* 100 41.57 



 

                           233 J I M D C   2 0 1 7  233 

C o n c l u s i o n  

This study provides us a clue that cromoglycate can 

attenuate the pro-contractile effect of insulin. So we 

suggest that pretreatment with cromoglycate may 

ameliorate respiratory adverse effects of inhaled insulin 

therapy in diabetic patients. Further clinical trials are 

warranted to confirm whether the protection offered by 

cromoglycate in guinea pig model can translate to human 

airways. 

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