Fibrinolysir (1991) 5, 177-180 @Wl Longman Group UK Ltd The Effect of Change in the Rhythm of Food Intake and Sleeping Time During Ramadan on the Diurnal Variation of Fibrinolytic Activity S. M. Bakir, M. M. T. Kordy, A. M. A. Gader SUMMARY. Consecutive measurements of blood coagulation and fibrinolytic parameters were undertaken at 9.00am, 4.OOpm, 9.OOpm and 4.OOam in eleven healthy subjects, observing the dawn to sunset fast of the holy Muslim fasting month of Ramadan. Measurements were repeated in an ordinary ‘non-fasting’ day. No statistically significant fluctuations were noted in prothrombin time, activated partial thromboplastin time, thrombin time, plasma fibrinogen, plasminogen, and tissue plasminogen activator (t-PA) either during Ramadan or in a non-fasting day. However, markedly elevated levels of the plasminogen activator inhibitor (PAI) activity were noted at 9.OOam in Ramadan and at 4.00am on a non-fasting day. Both increases were determined after several hours overnight sleep; the waking time in Ramadan being 8.3Oam and 4.30am in non-Ramadan day. Thus the circadian variation in PAI activity levels are influenced more by sleep pattern rather than food intake or the normal activities of a working day. KEYWORDS. Fibrinolysis. Diurnal variation. t-PA. PAI. Ramadan fast. Fasting during the holy Muslim month of Ramadan entails the abstinence from food and drink from dawn to sunset, approximately 15h daily. Such a fast is expected to produce some changes in those body systems contributing to the maintenance of body fluid volume and energy substrates. Several earlier studies have concentrated on body fluid,’ biochemical2,3 and haematologica13 changes associated with the Rama- dan fast, and none of them have considered haemo- static fluctuations. Previous studies have shown a significant increase in fibrinolytic activity when the body is exposed to mental and other forms of stress.4Y5 Studies employing tests of overall fibrinolytic activity i.e. those based on clot lysis time, have demonstrated enhanced fibrinolytic activity in the afternoon than the morning hours. 6,7More recently specific morning and afternoon fibrinolytic assays have established diurnal fluctuations in the levels of tissue plasmino- gen activator (t-PA) and plasminogen activator inhi- bitor activity (PA1 activity); peak levels of t-PA were recorded in the afternoon while those of PAI activity were found during the morning hours.8’9 Thus during Ramadan, the daytime fast with the accompanying change in the rhythm of food intake S. M. Bakir, M. M. T. Kordy, A. M. A. Gader, Department of Physiology, College of Medicine, King Saud University, Riyadh 11461, Saudi Arabia. and sleep is expected to influence the diurnal variations of the fibrinolytic enzyme system. This study was, therefore, designed to investigate this possibility. Measurements of fibrinolytic activity were taken during Ramadan and compared with those collected under non-fasting conditions. MATERIALS AND METHODS Eleven healthy volunteers were recruited from staff and students at the College of Medicine, Riyadh. All were males aged between 24 to 46 years (X+SD=34.9_+1.6yrs) and were all non-smokers. Their weights ranged from 56 to 90Kg (X+SD=72.4_+10.8Kg). They all observed the Muslim Ramadan fast which entails abstinence from food and drink from dawn to sunset. During Ramadan, the first meal (breakfast) was taken immediately after sunset i.e. approximately 6.00pm. The subjects were then free to consume food and drink thereafter, but were requested not to take meals with excessive amounts of fats on the days of blood sampling and to abide closely with the planned eating and sleeping hours. The volunteers retired to bed at 12.00pm midnight and rose at 8.30am. Their sleep was not, however, continuous; being broken at approximately 3.3Oam. At this time a light meal was taken and the dawn (Fagr) prayer given. Daily 177
Transcript
Fibrinolysir (1991) 5, 177-180 @Wl Longman Group UK Ltd
The Effect of Change in the Rhythm of Food Intake and Sleeping Time During Ramadan on the Diurnal Variation of Fibrinolytic Activity
S. M. Bakir, M. M. T. Kordy, A. M. A. Gader
SUMMARY. Consecutive measurements of blood coagulation and fibrinolytic parameters were undertaken at 9.00am, 4.OOpm, 9.OOpm and 4.OOam in eleven healthy subjects, observing the dawn to sunset fast of the holy Muslim fasting month of Ramadan. Measurements were repeated in an ordinary ‘non-fasting’ day. No statistically significant fluctuations were noted in prothrombin time, activated partial thromboplastin time, thrombin time, plasma fibrinogen, plasminogen, and tissue plasminogen activator (t-PA) either during Ramadan or in a non-fasting day. However, markedly elevated levels of the plasminogen activator inhibitor (PAI) activity were noted at 9.OOam in Ramadan and at 4.00am on a non-fasting day. Both increases were determined after several hours overnight sleep; the waking time in Ramadan being 8.3Oam and 4.30am in non-Ramadan day. Thus the circadian variation in PAI activity levels are influenced more by sleep pattern rather than food intake or the normal activities of a working day.
Fasting during the holy Muslim month of Ramadan entails the abstinence from food and drink from dawn to sunset, approximately 15h daily. Such a fast is expected to produce some changes in those body systems contributing to the maintenance of body fluid volume and energy substrates. Several earlier studies have concentrated on body fluid,’ biochemical2,3 and haematologica13 changes associated with the Rama- dan fast, and none of them have considered haemo- static fluctuations.
Previous studies have shown a significant increase in fibrinolytic activity when the body is exposed to mental and other forms of stress.4Y5 Studies employing tests of overall fibrinolytic activity i.e. those based on clot lysis time, have demonstrated enhanced fibrinolytic activity in the afternoon than the morning hours. 6,7 More recently specific morning and afternoon fibrinolytic assays have established diurnal fluctuations in the levels of tissue plasmino- gen activator (t-PA) and plasminogen activator inhi- bitor activity (PA1 activity); peak levels of t-PA were recorded in the afternoon while those of PAI activity were found during the morning hours.8’9
Thus during Ramadan, the daytime fast with the accompanying change in the rhythm of food intake
S. M. Bakir, M. M. T. Kordy, A. M. A. Gader, Department of Physiology, College of Medicine, King Saud University, Riyadh 11461, Saudi Arabia.
and sleep is expected to influence the diurnal variations of the fibrinolytic enzyme system. This study was, therefore, designed to investigate this possibility. Measurements of fibrinolytic activity were taken during Ramadan and compared with those collected under non-fasting conditions.
MATERIALS AND METHODS
Eleven healthy volunteers were recruited from staff and students at the College of Medicine, Riyadh. All were males aged between 24 to 46 years (X+SD=34.9_+1.6yrs) and were all non-smokers. Their weights ranged from 56 to 90Kg (X+SD=72.4_+10.8Kg). They all observed the Muslim Ramadan fast which entails abstinence from food and drink from dawn to sunset.
During Ramadan, the first meal (breakfast) was taken immediately after sunset i.e. approximately 6.00pm. The subjects were then free to consume food and drink thereafter, but were requested not to take meals with excessive amounts of fats on the days of blood sampling and to abide closely with the planned eating and sleeping hours. The volunteers retired to bed at 12.00pm midnight and rose at 8.30am. Their sleep was not, however, continuous; being broken at approximately 3.3Oam. At this time a light meal was taken and the dawn (Fagr) prayer given. Daily
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178 The Effect of Change in the Rhythm of Food Intake and Sleeping Time During Ramadan
working hours in Ramadan are from 9.OOam to 3.30pm. Blood samples during Ramadan were col- lected in the middle of the month when adaptation to the change in food and sleep rhythm was assumed to be complete.
On a non-fasting day, work starts at 7.30am and finishes at 4.30pm. Most subjects usually have a cup of tea and a light breakfast before coming to work. Lunch is between 1 to 2.OOpm, dinner at 8.30pm and bed-time is approximately at lO.OOpm. They wake up at 4.30am for the dawn prayer. Most subjects remain awake until they go to work.
Blood Sampling
Consecutive blood samples over a 24h period were collected at 9.OOam, 4.OOpm, 9.OOpm and 4.OOam, both during Ramadan as well as during an ordinary non-fasting day. Blood was collected directly in sodium citrate (0.11 M, Monovette system, Sarsdt, West Germany, 1 vol citrate : 9 vols blood) and was transported in ice-water, without delay, to the labora- tory. Plasma was separated in a refrigerated (WC) centrifuge and stored in aliquots at -40°C. All assays were performed within a month of blood collection. To avoid slight day to day variations in the assay techniques, tests were performed for each subject in both his Ramadan and non-fasting samples simul- taneously.
Haemostatic tests
The coagulation screening tests were performed using commercial reagents: prothrombin time (PT), activated partial thromboplastin time (AP’IT), (Diagnostica Stago, France) and thrombin time (TT, Parke Davis Topical Thrombin); the clotting times were registered by a coagulometer employing an optical system (Coagulation Profiler, Model CP-8, Bio/Data, USA). Plasma fibrinogen was measured by the turbometric method of Ellis and Stransky.” Fibrinolytic parameters were assayed as follows:
a) Quantitative (photometric) determination of tissue plasminogen activator (t-PA) was undertaken using the synthetic chromogenic substrate (CBS 10.65) technique which is supplied in the form of commercial kits (Stachrom t-PA SP - Diagnostica Stago, France). Calibration curves were constructed using purified t-PA and the results were recorded accordingly in IU/ml; b) Similarly the quantitative (photometric) deter- mination of plasminogen activator inhibitor (PAI) activity was employed using commercial kits (Stach- rom PA1 - Diagnostica Stago, France); c) Plasminogen was measured by a chromogenic assay (Coatest Kits, Kabi, Sweden). The instructions of the manufacturers of the kits used, were followed closely, without any modifications. The following physical parameters of the subjects were also recorded: weight, height, details of diet, physical activity and sleeping hours.
Statistical Analysis
The paired Student t-test was used to assess the data and statistical significance was assumed when PCO.05.
RESULTS
There were no statistically significant fluctuations in the coagulation screening tests: PT, AP’IT, IT and plasma fibrinogen, plasminogen, or t-PA, in the four daily measurements in Ramadan or in the non-fasting day (Table).
Plasminogen activator inhibitor (PAI) activity
PA1 activity in the non-fasting day was significantly greater in the early morning 4.OOam (XfSD=16.6f8.9IU/ml) than at 9.OOam (XfSD=6.3+3.1; P<O.O05), 4.00pm (6.8k3.4; P<O.O05) and 9.00pm (lO.Ok5.7; PcO.05).
Table The haemostatic measurements during a fasting Ramadan day versus an ordinary non-fasting day (n=ll)
Non-fasting Ramadan
Time 9.00 am 4.00 pm 9.00 pm 4.00 am 9.00 am 4.00 pm 9.00 pm 4.00 am
P value on comparing 4.00 am value versus others P value on comparing 9.00 am values versus others *=<0.05 **=<0.005 *<=0.05 **<=0.005
Fibrinolysis 179
During Ramadan significantly higher PA1 activity was recorded in the 9.OOam samples (X+SD=15.3+9.4IU/ml) than in samples taken at 4.OOpm (8.5k3.2; P<O.O5), 9.00pm (8.2+2.5; P<O.O5) and 4.OOam (8.0+2.2; PcO.05).
DISCUSSION
Fearnley and his associate@ and later Rosing et al,7 using tests based on clot lysis showed that fibrinolytic activity is highest in the afternoon (4.00pm) and lowest in the morning (4.OOam). These observations were confirmed by Kluft et al,*y9 who reported higher t-PA levels in the afternoon than in the morning. In contrast, the results obtained in this study did not show any significant diurnal variations in the plasma levels of t-PA when comparing morning versus after- noon measurements, either in Ramadan or during a non-fasting day. Closer examination of our results has shown that none of our subjects have depicted any significant increase in t-PA levels in either the fasting or the non-fasting measurements. Similarly, the t-PA levels in three out of ten subjects studied by Kluft et al9 did not exhibit significant diurnal fluc- tuations. It is possible therefore, that the variation in t-PA levels is a personal characteristic and that some subjects do not exhibit a significant circadian rhythm.
The daytime studies of Kluft and his associatessT9 reported higher PA1 activity in the morning (9.00am) than the afternoon (3.00pm). The same authors employing more frequent, 3-hourly, assays demon- strated that PA1 activity started to rise after midnight, peaked between 3.00 and 4.00am, then declined but remained high until 6.00am.” Further studies12,13 confirned the 4.OOam peak PA1 activity. Our results in an ordinary non-Ramadan day are consistent with these earlier reports. However, during Ramadan, with the shift in sleeping hours, the peak PA1 activity is recorded at 9.00am. It seems therefore, that sleeping plays a significant role in the circadian variation of PA1 activity, in such way that the characteristic delay in the sleeping hours that hap- pens during Ramadan, is accompanied with a shift in the timing of the peak levels of PA1 activity. The existence of such a mechanism was suggested in a recent study on the effect of shift work on the diurnal fluctuations of PA1 activity. It was shown that increases in PA1 activity were associated with sleeping whether the work shift entails a night or a day sleep. l3 The findings of all these studies taken together indicate clearly that the diurnal fluctuations in PA1 activity are related more to sleep rhythm than food or fluid intake or the ordinary physical activities of a working day.
Recently a pathogenic role for elevated plasma levels of PA1 activity was established in myocardial infarction4 and recurrent venous thrombosis.‘5 In addition, a higher incidence of the attacks of acute myocardial infarctio@ and sudden death17 was
noted more in the morning hours than in any other time of the day. This coincides with markedly enhanced platelet aggregability” and as detailed above, also with heightened PA1 activity. We could not find any documentation on the incidence of myocardial infarction in the morning hours in Arabs. It is therefore difficult to speculate whether the shift in PA1 activity reported in the present study would be accompanied with a shift in the timing of the occur- rence of myocardial infarction.
In conclusion, the results of this study have shown no significant diurnal variations of the plasma levels of plasminogen and tissue plasminogen activator. Peak levels of PA1 activity were recorded in the morning hours with a delay in peak levels related to the delay in waking up time.
ACKNOWLEDGEMENTS
We would like to thank Messrs. M. A. Hamid and L. A. Gassem Al Seed for their excellent technical assistance; and Mrs. F. Chatila for typing the manuscript. This work was supported by a grant from the College of Medicine, Research Centre, Riyadh.
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Received: 11 Julv 1990 Accepted after revision: 25 November 1990 Offnrhrt orders to: Dr A. M. A. Gader. Professor of Phvsioloav and Director of the Blood Bank, College of Medicine and King Khahd University Hospital, P.O. Box 2925, Riyadh 11461, Saudi Arabia.
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